Looks like a standard ATX type of PSU so easy to come by, couple of questions first though;
Are you having computer issues such as the computer not powering up at all, if yes, let us know the exact issue that you are having.
Is the computer a custom build or a brand name such as Dell or HP etc, if a brand name, post the brand and model name or number, if a custom build, what size of case do you have, small form factor, mid or full tower.
Do you have an add on video card fitted, if yes, what is the brand and model name or number.
In which country will you be making any potential purchase.
Having the answers to all of the above questions will help to best advise you.