gray and white screen of death

It is unlikely that the registry cleaner is the culprit as the computer has apparently run satisfactorily since cleaning.

The use of Registry cleaners should be avoided except in very specific circumstances. In gereral terms cleaning the registry will not improve performance perceptably if at all and. in the wrong hands can lead to an unbootable computer. Steer well clear of them

Your issue is most likely hardware based and I would initially suspect the PSU - Power Supply.

Can you give us detail of exactly what happens when you power up the computer - which is a desktop?? ....

Do you hear the fans start up? If not remove the side of the case and take a look.

Does the power light come on and stay on?

Does the hard drive light flash indicating activity?

Does the light on the optical drive (CD/DVD drive) flash when the power switch is pressed.

I would normally ask if the power LED on the motherboard is lit, but we do not have your system details so cannot check if there is one.

We encourage all members to complete their System Specifications which help us to help you

Providing that the hard drive has not failed your data can be recovered by slaving the drive to another computer.To soon to comment on that without the info above.