Fired before my first day of work?

What is the name of your state? California

Actions
1. Signed offer letter of employment.
2. Sent signed offer letter to new employer.
3. Gave 2 weeks notice to current employer.
4. Passed mandatory medical and drug screening by new employer.

Result
1. Was notified four days before 1st day of work by new employer that the position previously offered to me was no longer available.

Question
1. Am I entitled to signing bonus as written in offer letter?
2. Am I entitled to two weeks pay or more?

thanks

You're not automatically entitled to anything under any statutes or laws.

You might have a civil cause of action for "detrimental reliance" but you'll need to consult with an attorney on that. If you were able to rescind your resignation with your current employer however, you'll have no damages to demonstrate and thus no action to pursue.