I don't have mig hopes for you to restore the sound even to make it understandable.
It sound like it's either recorded at way too high level, so that it distorts from being cut at the max level, or recorded at too low level through a device that filters out near-silence so that it's cut at the min level.
In either of those cases you have lost a lot of the data. Also, it sounds like it has been compressed quite a bit, which removes even more data.
You could try to adjust the level up or down depending on what the problem is, and applying a band-pass filter to single out the voice frequencies from some of the noise. Then you will see if there is enough left to be made understandable.
This should be available in most programs that can edit sound. I used GoldWave many years ago, but I don't know if it's still around...