How do I resolve the this situation?

You should consult an immigration attorney because there can be significant immigration consequences for changing employers.

I don't see a lawsuit here. The store is not required to assist you in finding lost items. If you have some evidence that they know they have the...

Can a company reduce your wage without notice???

Yes, employers can reduce future wages without notice, assuming you don't have a contract with them, and they don't reduce the wage to below...

Can I sue my previous employer for wages lost or personal grievance?

Unfortunately, I don't see a promise from FD which you reasonably relied upon to your detriment which is what you need to establish promissory...