@ja-luikinga Are you getting a specific error message? Are the WAV files still available?
I'm not sure if you can import HDP files into a VIP project, in case you want to do this. Maybe it is better to export your WAV first and load that into your project.
. . . . I cannot open my hdp file what is the best way . . . .
This would suggest you are trying to open a project file for Samplitude - is this correct?
If so the project file has the .VIP file extension - @SP. has mentioned the VIP project file in the comment 3 above this one.
The HDP file is a supplementary file created when you import, for example, a WAV file into the program, this is the same with many other Magix programs.