I have a case going on, the lawyer who I hired left the firm is it legal for them to hand my case over to another lawyer, or can I get my money back

If the lawyer you retained has left the firm, you have the right to tell the firm that you want the first lawyer to continue to handle the case, and to send the retainer and the file to that lawyer, or you can stay with the lawyer in the firm that they assigned to you, or as a third option, you can ask for the return of your retainer and hire a completely new lawyer.