I have been playing MM3 had my party built up in their stats. All of a sudden their all old (113 years) with very low
stats from touching certain crystals in the pyramids. The Fountain of Youth will NOT restore their
ages. This is their real age (not magic age ?) - it will not lower by
drinking at the fountain of youth. Their real age was 35 before I
noticed the change. Any way to reverse this?
Any info will be
appreciated. Thanks.

Those crystals actually cause time to advace really quickly; it seems that 78 years have passed, causing your characters to, of course, be 78 years older.

Unfortunately, the only way to reverse this is to use a hex editor and edit the current year backwards.

(Note: Characters under 18 will suffer stat penalties, so you don't want to set the clock back too much.)

I installed Hex Editor for the Notepad ++, but I don´t understand where do I alter the year information.

I know this information here: | Jahr im Spiel 11887,11888 2e6f,2e70 |

But I don´t know how to alter it...

The year value is stored at offset 11887 (0x2E6F in hexadecimal notation). It is a 16-bit value, and thus also covers offset 11888 (0x2E70).

At the start of the game, the year is 500, which in a hex-editor would show as F4 01.

Your characters start out 18 years old, so if they now have a natural age of 113, the year should be roughly 595, which would show as 53 02.

If you want the year to be 517 (giving your characters a real age of 35), change it to 05 02.

It worked!!! Finally I can continue my quest! Thanks a lot!! I hope I will be more careful from now on.