If you are unable to boot your Windows 7 to create a Windows 7 System Repair Disc, then you could create it on another computer to use on your computer."
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Then use that Disk for the System Recovery Options:
"System Recovery Options"
http://www.sevenforums.com/tutorials/668-system-recovery-options.html
"How to Run a Startup Repair in Windows 7"
http://www.sevenforums.com/tutorials/681-startup-repair.html
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Why don't you know the Product Key?
It should be on the Sticker.
The COA sticker is either on the underside of the Laptop or in the Battery Compartment.
With a Desktop it is either on the side, rear or top of the Computer Case.
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And if the Hard Drive is OK, there should be a Recovery partition to reinstall the Operating System from if it is a Branded Computer, HP, Acer, etc.
Here are the Key/s to press at Boot to start the Recovery Process back to Factory Settings (new condition). Under each Manufacturer in the list below are the instructions in the respective links for you to
follow on how to use their Recovery Partition
Acer – Press Left Alt + F10 Keys.
http://acer.custhelp.com/app/answers/detail/a_id/2631
Advent – Tap F10 until Starting System Recovery appears
https://answers.yahoo.com/question/index?qid=20081221054701AAJT8YV
Asus – Press F9
http://support.asus.com/Troubleshooting/detail.aspx?SLanguage=en&m=X53E&os=&no=1775
Dell – Press F8 which will bring up Advanced Boot Options
http://www.dell.com/support/troubleshooting/us/en/19/KCS/KcsArticles/ArticleView?docid=DSN_362066
eMachines: Press Left Alt Key + F10
http://techchannel.radioshack.com/emachines-system-recovery-1747.html
Fujitsu – Press F8
https://forum.ts.fujitsu.com/forum/viewtopic.php?f=64&t=39428
http://support.ts.fujitsu.com/WDB/FAQContentstart.asp?ID=233412526&WDBStatID=&INFO=SA&quest=&Sprache=en&SprachID=&SecID=&lng=COM&Todo=FAQ
Gateway: Press Alt + F10 Keys - As Acer owns them: press Left Alt + F10 Keys as per Acer eRecovery
http://www.ehow.com/how_6960920_restore-computer-using-recovery-partitiion.html
HP – Press F11
repeatedly
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01867418&cc=us&destPage=document&lc=en&tmp_docname=c01867418
Lenovo – Press F11
http://support.lenovo.com/en_US/detail.page?LegacyDocID=MIGR-4M7HWZ
LG – Press F11
https://answers.yahoo.com/question/index?qid=20090304161820AAiyvMn
Packard Bell: Press and hold the ALT key while
pressing repeatedly the F10 key. Release the keys when a message displays that Windows is loading files.
http://packard-bell-scandic.custhelp.com/app/answers/detail/a_id/3068/session/L2F2LzEvdGltZS8xNDA2MjgyMjczL3NpZC90Z205SDktbA%3D%3D/~/use-packard-bell-recovery-management-to-restore-your-system-or-create-recovery
Samsung – Press F4
http://www.samsung.com/us/support/howtoguide/N0000137/6375/93514
Sony Vaio – Tap F10 until the Edit Boot Options screen is displayed
https://ca.en.kb.sony.com/app/answers/detail/a_id/35585/p/48903,49902,71663,71664/c/65,67/kw/recovery%20using%20f10
Toshiba – Press 0 (zero)
http://forums.toshiba.com/t5/System-Recovery-and-Recovery/How-To-Perform-system-recovery-Windows-7/ta-p/279643
Cheers.