How can someone start writing without any ideas? What is the first step in the writing process?

I suggest you either read a bunch of books, watch a lot of movies / tv shows, or go online and use a brainstorming tool. The goal is to get your creative juices flowing again.

If none of that works, go through your old work – the stuff you’ve started but never finished – and see if there is anything in there that could get you started again.