The point of going to see a therapist - which many people have suggested - is not in "treating" your being "talentless" as a mental health condition, but in helping you get grounded and in touch with reality. You write extremely well - the last post shows it. You also report very high verbal scores, consistent with the writing you have demonstrated on this thread. I do not know about piano and other pursuits in which you report having failed - I cannot hear you play, and, being talentless and without a musical ear myself, I would not be able to judge your performance anyway. But with writing you clearly have it in you, and, given that you report high verbal scores, the issue with your writing seems to be two-fold: lack of solid executive skills and paradoxically low self-esteem. A therapist can help with the latter. For the former, since you are in college and have access to free resources, I would first contact the learning resource center and see if they have anybody who could help you with executive functioning.

Also in the last sentence of your last post you endorsed some degree of depression, which unlike being talentless is a mental health condition.

I would suggest printing out this thread and taking it to the school's counseling office.