Pc stuck in sleep mode...

My brother loaned my kids his pc. He had his sleep options set too high at 10 mins for screen, 25 mins for hard disks and 45 mins for system standby. I decided to change them. I checked on the internet and followed the directions. I went into power options and changed the screen to 20 mins I think, and 3 hours for the other two. I may have also enabled hibernate. Now his pc has shut off and won't come back on. The monitor read... 1. digital annalog..sleep mode...hit any key or move mouse.... This however, didn't do anything. The screen's power button is orange. I unplugged it for 10 mins and it started to reboot afterwards. I got a message about ...power loss...scroll down to choose which program to use...and I didn't know which to choose so I didn't choose any. Then it went back to sleep. I unplugged it again, but all it does now is beep. Six beeps I think and the numbers 3 and 4 are lit up on the front. Please help me fix this!