I was found to be at 75% fault in a accident resulting In the victims death. Can I claim compensation? It has also ruined my life.

If you were in an accident which resulted in a death and you were 75% at fault, I hardly think you can claim compensation for anything related to the accident. I am sure it has had an impact on your life, another life has been lost. Who would you claim compensation from, your insurance company had to pay out.

Also, if you were found to be "75% at fault", I would guess that this was a civil suit. If so, you were not found "guilty", because that term only applies to criminal cases. You were negligent.