Computer will not boot after disk defragmentation

Thanks for the replies so far.

The problem is that it does not even allow me to get into bios nor does it boot from any drive. Can it be a problem with the ram or motherboard?

It is certainly a possibility.

One thing to try:
With the computer turned off and unplugged, detach the ide/power cables from the CD, Hard, and floppy drives. Turn it on.

Do you get a screen? Do you get a POST beep of any kind?
If so, plug the devices back in one by one.

If not.. what do you get?

Ok here is the update. I replaced the RAM which did not solve the problem. I did manage to get into the bios by disconnecting the hard drive. So it seems as if it is a problem with the hard drive itself. I am going to install a new one tomorrow but the thing is that there was a lot of important data on the old drive. Is there a way to copy the data if i am unble to use the old drive as the slave drive?

Also can someone post on the specific instructions to use the old drive as a slave. I am pretty sure I know how to do it but just to be 100 percent positive because the data is irreplaceable and consists of years worth of work.

Never made a backup, he?

Look into the program "HDD Regenerator from http://www.dposoft.net/
One of, if not THE, best for reviving HDs.

To use a former Master as Slave, all you need to do is change the jumper next to the IDE-cable on the back of the HD. Most HDs have a picture/diagram printed on them, showing you how to do it.
Go into BIOS, to check that the 2nd HD on that ID-channel has been set to "automatic detection".