Legal Question in Real Estate Law in California

Ordinarily, no, not without adverse consequences at least. There are several possibilities with varying likelihood when a seller backs out, or tries to back out, after signing a contract:

1. If the contract is for the sale of real estate, the jilted buyer often may be able to sue for "specific performance," a remedy which requires the seller to convey to the buyer, provided that the buyer is ready, willing and able to uphold its end of the bargain, i.e., is ready to pay the agreed-upon price or obtain the agreed-upon financing;

2. If the contract is for the sale of personal property (anything other than real estate), the buyer probably cannot obtain specific performance (there are exceptions), but can sue for damages, usually money damages, which will be awarded based upon the harm suffered by the would-be buyer -- which may be well less than the value of the goods or the contract price, since in many instances the buyer would be able to obtain similar goods from another seller without significant loss.

3. Sometimes, but rather rarely, the seller can back out of the deal after the contract is signed without liability to the buyer. Such instances often involve buyer fraud, contingencies in the contract that weren't satisfied, or other legal or factual circumstances that render the seller's performance impossible or excused.

No, not based on the scanty information that you provided.

Sure, anybody can breach a contract. If you think you can win and it is worth suing, then that is your remedy if you can't work it out informally. .