F2 or the Delete key will both let you enter the BIOS. But those keys do not cause any display to start on a monitor, you should see several different displays on the screen when you turn on the PC before Windows starts.
Turn on the monitor before you turn on the PC. Is the monitor set to the correct input? Are the cables connected right? Does the monitor display a "No Signal" message?
It sounds like the PC has more problems than being sluggish. It doesn't start Windows either, does it?
Turn off the PC's power supply with it's switch on the back of the PC, and wait 30 seconds. Then disconnect the AC power cable. Let it sit for 30 seconds, and then reconnect the cable, turn on the power supply, and try the PC again. If you can't get any display, try another monitor if the PC seems to be running (turn off the PC when switching monitors.) If that fails we'll take it from there.