When the input file refers to these files, then they have to be ASCII files. Use an ASCII editor to open them. Or run a datacheck and look into the .pes file or open that with /CAE.
If that is not working, then maybe the creator of these files has encrypted them to protect the informations inside. Then you have to contact this person.
See Abaqus Analysis Users Guide 3.2.42 Encrypting and decrypting Abaqus input data