Long shot--make sure the caps lock key is off. There are ways around this. Someone else will jump in to help or google windows password. If you post back, mention the operating system.

It has to be your log on, the PC won't change by itself.   The official Microsoft response to not having the correct log on is a complete reinstall.  There are hacks around but it's beyond the Terms of Service of this forum to discuss anything illegal.    The Microsoft reasons is, if there were a way to get around the log on then  anyone potentially could access the PC.

Double or triple check the name/password.  If it was all lower case make sure the caps lock is not on, etc.

Was the system stored without being plugged into the wall for those 4 months?

In that case the motherboard battery may have died and things stored in BIOS may have gotten scrambled. Try just pressing Enter when asked to log in.

And you may need to replace that battery.

Ron

Thanks much.  Appreciate your input.  I completely understand that anyone could access any computer if it were easy to get around the log in.  I've tried everything that everyone has suggested (all caps, lower case, different 'possible' log in names, etc.)  to no avail.  One response was that since the unit was stored (not plugged in for 4 months) that it could be the battery.  That's the only 'odd man out' option I have received so far, but will keep checking.  Again, thanks very much for you input. I'll keep trying!