Registry Cleaner How Long Does it take

How long does it take to do a clean and how long wil my computer be down for. Its still stuck on loading screen . Black screen help tried rebooting nothing

Which Registry Cleaner?

It looks to me the OP is using GrimeFighter which is obsolete for about 8 months.
If the OP is using GrimeFighter, it should be removed and replaced by avast CleanUp.