"To continue, type an administrator password, then click Yes"

If there are no Administrator accounts on the system, you can boot to Safe Mode to access the Built-in Administrator account.  From this fail-safe account, you can force-reset your account's password.

1. Press +I to display the Settings charm menu.
2. Click the Power Options icon, then hold down the Shift Key while you click the Restart option. Keep holding shift until the screen says it is restarting.
3. On the first screen that appears, select Troubleshoot, then select Advanced Options. Finally pick Startup Settings and click the Restart Button.
4. On the next screen, press the Number 4 Key to choose Safe Mode.

Now that you are in safe mode, you can use the built-in backup Administrator account to perform you necessary recovery. The built in Administrator account should not be used for any other purpose, or it won't be available in situations like this when you need it.

1. At the login screen, click the Arrow Icon and select the Administrator account.
2. After Safe Mode starts, press +W and open Control Panel / User Accounts.
3. Select Manage another account and select the account you wish to change to an Administrator account. You can also use the Change Password option here to reset the other account's password.

When you're done, restart the computer normally.

Thank you Shawn for your reply.

My computer logs me in automatically, but when I've logged out and I then go back to the login screen, I'm given my account, and the regular icons at the bottom (while in Safe Mode):

I don't know where the Arrow Icon is, or where it's supposed to be.

Hello Rachael,

Thank you for keeping us updated on the status of the issue.

You should require a Windows 8 DVD or the USB to fix the issue.

If you don’t have a Windows 8 DVD, you can refer to the article mentioned below to know how to create a bootable USB for Windows 8.

How to create installation media for a PC refresh or reset
http://windows.microsoft.com/en-us/windows-8/create-reset-refresh-media

Contact your computer manufacturer to get the product key or the installation disc

I suggest you to change the first boot priority to DVD\USB if you are not able to get the boot menu when you insert a DVD\USB.

Note: Modifying BIOS/ complementary metal oxide semiconductor (CMOS) settings incorrectly can cause serious problems that may prevent your computer from booting properly. Microsoft cannot guarantee that any problems resulting from the configuring of BIOS/CMOS settings can be solved. Modifications of the settings are at your own risk.

Please follow these steps and check if it helps.

a. Boot from the Windows 8 DVD.
b. Once you get the welcome screen of installation with the option “Install now”
c. Click on Repair your computer
d. On the next page click on Advanced Options
e. Now click on Troubleshoot
f. Click Command prompt.
g. In command prompt, type the following command and press Enter.

net user administrator /active:yes

h. Exit command prompt and restart the computer.

If it does not help, then perform system restore from advanced options.

Please follow these steps:

a. Boot from the Windows 8 DVD.
b. Once you get the welcome screen of installation with the option “Install now”
c. Click on Repair your computer
d. On the next page click on Advanced Options
e. Select System Restore and check you can start the computer.

Note: When you use System Restore to restore the computer to a previous state, programs and updates that you installed are removed.

I hope this information helps.

Please do let us know if you need any further assistance.

Thank you

Hello Ratandeep,

Thank you for your reply

I cannot run the Windows 8.1 Setup program, as I'm greeted with the pop-up 

"You must be logged on as a member of the Administrators group of this computer in order to run this application"

Where can I go from here?

Thank you

Hello Rachael,

Thank you for your response.

Did you try using all the suggestions provided in the previous post?

If you are able to get to the command prompt, I would suggest you to disable User account control(UAC)

from command prompt and then try to run the setup.

Please type the following command in command prompt and press Enter.

C:\Windows\System32\cmd.exe /k %windir%\System32\reg.exe ADD HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System /v EnableLUA /t REG_DWORD /d 0 /f

I hope this helps.

Thank you

Hello Ratandeep, 

Thank you for your continued support.

Yes I have, with no success.

I can only get in the regular command prompt, and not in 'run command prompt as administrator'. I've tried typing that whole command in, but it says:

'C:Windows\System32\' is not recognised as an internal or external command, operable program or batch file.

Is this a problem with my lack of admin rights?

Thank you

(PS: Some aspects of Acer ArcServer have apparently been blocked by my firewall and there's no way for me to actually allow access. There has also been the Windows 8.1 Update that has been trying (and failing) to install since the 9th of April, and I hear it needs to be done by May 13th. Not relevant, but I'm worried this may really mess up my computer.)

Hello Rachael,

Thank you for the update.

I would suggest you to create another user account from command prompt and check if it helps.

Please type the following commands and press Enter after each:
    
net user "Jack" xxyyzz /add
(to create an account with a password of xxyyzz)
    
net localgroup administrators "Jack" /add
(to make it an admin account)
    
net user Jack 123456
(to change the password to 123456)

Note: You may change username and password as per your requirements.

I hope this information helps.

Thank you

Hello Ratandeep,

Thank you for your continued support.

Upon typing the first step, I'm given "System error 5 has occurred. Access is denied."

Thanks in advance

Hello Rachael,

Thank you for the reply.

I would suggest you to reset BIOS settings and check the issue. Please use these steps:

a. Turn the Acer Aspire laptop on. Restart it, if it is already turned on.

b. Press the "Del" key as soon as the computer turns on. The BIOS setup utility will load.

c. Press the "F5" key to reset the BIOS to default values.

d. Press the "F10" key to save the changes and exit the BIOS setup utility.

Note: Modifying BIOS/ complementary metal oxide semiconductor (CMOS) settings incorrectly can cause serious problems that may prevent your computer from booting properly. Microsoft cannot guarantee that any problems resulting from the configuring of BIOS/CMOS settings can be solved. Modifications of the settings are at your own risk.

I hope this information helps.

Thank you

Hello Ratandeep,

Thank you for your continued support.

I've reset BIOS settings, retried the command and I still have the same error.

Thanks in advance