Hi Priya. I'm Greg, an installation specialist, 10 year Windows MVP, and Volunteer Moderator. If you will work with me I will be here to help until the issue is resolved.
Try all other ports on the PC, often the front and back will have different USB controllers
Power off by holding in the power button twice, on the third time it should enter Recovery Environment which has a better chance of the mouse and keyboard working.
If so choose Advanced Troubleshoot Options to try to System Restore to a point when it was working:
https://www.tenforums.com/tutorials/2294-advanc...
If that fails try to enter Safe Mode by whatever methods works here:
https://www.intowindows.com/boot-windows-10-in-...
https://www.digitalcitizen.life/4-ways-boot-saf...
In Safe Mode enter Device Manager reached by right clicking the Start button, choose the Mouse and Keyboard devices, then from Driver tab try Update Driver > Automatically, then if that fails Update Driver > Browse > Let Me Pick to try all previous installed drivers. If that fails then try to Uninstall the driver and restart PC to see if device works now.
If this fails then from Device manager try uninstalling the USB controllers, restart PC to reinstall. First program the power button to Shut down the PC at Settings > System > Power & Sleep > Additional Power Settings > Choose what Power button does so you can do the restart from it.
If that fails try another mouse and keyboard. Repeat the above steps if necessary to see if they work better.
If not then go into Troubleshoot Options to do a Reset, saving files if not backed up:
https://www.zdnet.com/article/windows-10-tip-re...
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It may be necessary to create bootable media to access Repair Mode or do the Clean install since it relies on different drivers that will often cause the keyboard and mouse to work.
To create Windows 10 Installation Media on another PC install Media Creation Tool and follow the directions here:
http://windows.microsoft.com/en-us/windows-10/m.... Uncheck the box for Recommended Settings to choose the exact version and bit rate for the target PC only.
Insert media, boot it by powering up PC while pressing the BIOS Boot Menu Key:
https://www.sysnative.com/forums/hardware-tutor...
If the media won't boot you may need to enter BIOS/UEFI Setup (pressing key given in chart in link above) to turn off Fast Boot or Fast Startup first.
Choose the boot device as a UEFI device if offered, on second screen choose Repair Your Computer, then Advanced Troubleshoot Options, then System Restore.
If that doesn't help follow steps in the Safe Mode guides above to try to get into Safe Mode. If that fails go back to Troubleshoot Options to try a Reset.
If that fails choose Install Now, then Custom Install, then at the drive selection screen delete all partitions down to Unallocated Space to get it cleanest, click Next to let it create needed partitions and start install - this makes it foolproof. Everything needed to get the best possible Clean Install is here:
http://answers.microsoft.com/en-us/windows/wiki.... It is a better install than any amount of money can buy and a great learning experience that will make you the master of your PC because you will learn what works best and how to apply it with your own hands.
If you need to rescue your files use this method:
http://answers.microsoft.com/en-us/windows/wiki...
I hope this helps. Feel free to ask back any questions and let us know how it goes. I will keep working with you until it's resolved.
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