My ipod touch 5G camera doesn't focus

I bought online an Ipod touch 5G like 3 or 4 months ago, and it was perfect, but now the back camera doesnt focus anymore, it take pictures from far really nice, but when I try to take a picture of text of something it wont focus, and the front camera focus the text perfectly, I already restored it several times, and i've cleaned it, I dont know what else to do.