how to rollback last update sql query i did

Question

Its very urgent for me.....

update ProductSerial set BranchID=2 where BranchID=4 and ActivatedSystems=0 and CustomerID=1 and ProductID=19

this is the query i have to run.....instead of that i did..

update ProductSerial set BranchID=2

it my online db.....i have to recover it from previous stage....