Have you tried accessing the advanced start-up options (usually by pressing F7 or F8 while the PC is starting up) and select "Last known good configuration"?
If that's not accessible, then it appears that you would need to try to perform a start-up recovery procedure using the installation disc that came with your PC. There are instructions in the disc on how to perform a start-up recovery.
If that doesn't work, then it's possible that critical OS files have been corrupted (either by the virus or by forcing the PC to shut down). If you can access the "Tools" from the Installation Disc, use the following in command prompt:
1. sfc/ scannow
2. chkdsk /r
If #1 doesn't work, then restart your PC and try #2.
If these don't work, then you would need to reinstall everything. OR, if #2 says your drive is failing, then you would need to have your hard drive replaced before reinstalling everything.
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