There are registry cleaners and then again there are registry cleaners.
In my experience most do not do as well as reinstalling your PC from scratch. Some can solve problems you are experiencing, but the reinstall tends to solve them with less risk. Some find things that are not a problem and claim it is, so probably worth avoiding those who scare you into thinking there is a problem, and want you to buy their product in order to solve it.
CC mentioned above is free, and does an adequate job. But don't fix what isn't causing you a problem.