Apart from psychotherapy, what treatments are available for anhedonia caused by drug abuse?

Do it til u feel it: Support groups (aa, na), exercise, other healthy activities, eating healthy, sleeping enough, sober fun... Even if you don't feel like it, getting in a routine of healthy activities will help. Acting your way into feeling better and thinking more clearly is far more effective than waiting until you think or feel differently so you can do things differently.

Not enough info: First, it is far more likely that drug abuse would be caused by depression/anhedonia than the reverse. If the drug abuse is ongoing, that is the first problem to tackle. If it is a thing of the past, then the cause of anhedonia is an open question, something that warrants a thorough evaluation with a professional.