Do you know his address?
Does he trade as a limited company?
Are they a limited company?
To whom did you pay the deposit?
Do you know how long they have been trading?
You can always sue them.
There is always a risk with limited companies because they can close down but if they have been trading for three years that is not all that likely.
You don't need to use a solicitor. You can claim at the small claims court and self represent. This is not a complicated case.
That said, there are no other ways of forcing them to pay if they are unwilling.
You could always send them a letter before action which might be effective.
But if they ignore that then the only way to get a judgment that you can enforce is to sue.
You can issue here
Can I clarify anything for you?