Legal Question in Real Estate Law in California

Re: Changed the Locks

Who has the primary right to the apartment? Are you both on the lease? If so, see the landlord. If your ex is the tenant, you were either her subtenant or her guest. If you were a subtenant, formal eviction procedures must be used -- get help from the landlord, a lawyer, or small claims court. If you were a guest, your rights are very limited and you can't re-invite yourself. Whether you were a subtenant or guest depends on whether you were paying any rent and other facts.

Cashing checks on your account is probably forgery. Contact your bank -- many banks will reimburse their customers for losses sustained through forgery. If you feel strongly about it, contact the police or sheriff white-collar crimes unit after dealing with the bank to initiate a criminal complaint against the ex.

Putting your things in storage may have been improper. If you were a tenant or subtenant you should get them back at no cost to you; it is a basic rule that landlords must protect tenants' belongings at the landlord's expense and risk.

Giving you full advice covering all possible situations is impossible on a bulletin board but if you have given an unbiased story in your question your rights seem to be violated and you should get some results addressing your problem in the right forum -- landlord, bank, police, small claims, or lawyer. Good luck.