hi there, the problem could be many folds, but perhaps we can narrow it down.

first of all, it is always easier when we know what kind of computer it is, how old it is, and finally, the operating system(meaning, Win98, WinME, WinXP, etc.,) it makes trouble shooting easier

if you've replaced the soft cell(which I think is the RTC battery) about an year ago, it should be fine.

try this first:

take off your power cord. Press the start button and keep your finger pressed on it and count to 30 very slowly.

Replug and start...

this is a might solve your problems. If NOT...

try this:

as soon as you turn on your computer, tap F8 key repeatedly...it should take you to a black screen eventually(this is if you are running WinXP) and then you can boot to safe mode.

If it'll let you boot to safe mode, your problems could be software/malware/virus/driver issues

if it won't let you, then it could be other issues

(I would suggest booting from a DOS diskette/CD rom/Hard drive, but we are not sure of a few things...your computer type, your OS system, the age, what kind of booting roms you've got, etc., but perhaps someone with expert know how can try it and trouble shoot to see if it is hardware problems)

then try this:

did the computer come with a restore disk? If so, put the CD rom in and restore it from there(once again, different OS will do it differently, for example, older computers with older OS system will require you to hold the C key to boot from the CD, while XP should boot from the CD(not always the case but usually) Don't do the R in the first screen, agree to the licensing stuff and then make sure you select the right partitions. Follow the protocols and try to repair.

if that fails, then we can narrow it down to the following:

if your computer is more than 5 years old, these could be the problems:

1)the capacitor's aging and have dried out. IF this is the case, then swap in a whopper power supply might do the trick and will be the cheapest

2) could be motherboard(then you'll have to take it in to someone who is professional)

3) open your tower, unplug all external hardware such as CD/DVD drives, diskette drives, unplug all usb cords(except for mouse and keyboard if you connect this way) (if your computer boots fine, then you should start looking at the issues this way)

4)if the above fails and you are sure you don't have any viruses and all your updates are good, your device manager is fine, and everything else runs...

take out a gun, point it at the computer, shoot it and take it out of its misery
(but say a prayer for it and bow your head and mourn, ya know? )

hope that helps

(it could also be something that is very simple that an expert can trouble shoot and would only take a push of a button!)

Good luck!