PEAK files don't work

I have just re installed my computer with windows 10 and cubase 5. I have add my back up files, but all my .wav files have turned to PEAK files. And cubase can’t find them.

Is there something I have missed in the installation?
Or has my backup screwed me up?

Many thanx in advance

.wav files don’t turn into peak files. These are two different things. If your wav files are missing, you haven’t backed them up correctly, or they are in a different folder now.