What do you when you cannot find the artist of something?

[xxxxxxxxxxxxxxxx]

Jup. Open the Google image search in a new window, then drag and drop the picture into the search field. (The image you want the artist of, not the signature.)
It works best if you have an internet source for the picture, since it will take the page where you found it into account as well, but you can also upload it from your PC and see if it can find similar pictures or a source. (If you didn't change the name of the picture when you saved it)

Or, just show us the original picture. It might be easier for someone who knows the artist to identify one of his works than the signature...or at least someone could give you keywords to search for, say, if it's a special style like "art nouveau" or "trash polka"...