Does it still have a 'Property of RSCH' sticker on it?
If so, phone the hospital IT department, explain that you bought it from a guy who said he works for the hospital, and ask them if they know the password.
Make sure you give them your correct name and address when they ask for it...
So. you want to hack into a computer password, and want to drag me into your illegal scheme? No way!!!
Try emailing Julian Assange and asking him for advice, but leave me out of this. :ffsparr:
If you don't know enough to check whether to buy a 32 or 64-bit version of windows, just stop.
Take it to a local store, ask them to install XP, Win 7 or Win10, whichever you prefer. It will be much, much cheaper than the route you are taking.
My best guess is...
1. you have actually bought a disc containing a whole bunch of drivers.
2. The disc has wrongly installed the wrong drivers for your graphics card.
Solution? Re-start / boot up into Safe Mode (with networking), let the PC continue installation of whatever drivers it thinks...