i don't rightly know what i've done. i have tried on many save but i can't earn any money from quests or contracts.
any help or response is appreciated!

If you are using Galaxy, use the game integrity check feature. Or, copy recent game saves and store them elsewhere. Then, delete and reload the game and copy your saves back over. If the game files have been updated, the game-saves might not be compatible. You may also try reinstalling the older "Classic" version of the game to see if your saved games run.

If you wish to avoid this sort of conflict in the future and are using Galaxy Client, either delete the client or uncheck its auto-update feature and check periodically that it remains unchecked and will not update the game without your consent.