Tax question---employee stock purchase plan

I have sold the stocks through employee stock purchase plan (ESPP) last year. Thanks god I even get some gains. But the company deducted more than 30% tax for the gains I got. On the other hand I did some bad investment trade in the stock market which I lost significant amount of money. Overall I lost in the investment activity (if ESPP also considered as my personal investment).

So my question is, how should I claim the tax deducted by the company back to my own pocket?