Music isn't art. It's a tool to solve a problem. Not knowing what to compose is a solution looking for a problem. Generate ideas by getting out into the real world and finding out the pain points in life. Compose scores to accentuate those problems. Preferably, pick a problem which people are willing to pay money to have portrayed musically.
Still not thinking of anything? Go outside and play until you find something.
Still not thinking of anything? Go outside and play until you find something.