Next time when the system is booted, hit the key <F8> during the boot-up. This will cause a menu to appear, retry it if it doesn't appear. When it does it should be a menu, select "safe mode" and allow it to boot. Hopefully, it continues and enters safe mode display. Once there use the "restore point" feature and enter a date before the problem happened. Hopefully, you can recover and all is well. If not, then just got you to this point, some new s/w, or h/w or installed something, recent lightening storm, power glitch, constant or any beeping, please inform if you can. it always helps to know and pass it on.

tada -----Willy Happy