Transformer can handle power flow in both the directions, forward and reverse. This actually happens in case of interconnecting transformers. Either of the two windings can become primary (drawing power from source) and the other winding becomes secondary, delivering power to load. So it is bidirectional.

Do transformers work both ways?

Yes, it works in the opposite direction. However, do not exceed its original ratings, both voltage and current. Suppose you have a transformer rated for 120 V in and 12 V out, a 10:1 turns ratio.

Does a transformer work only in one direction?

Assertion (A): a step-up transformer cannot be used as a step-down transformer. Reason (R): A transformer works only one direction. Assertion (A): a step-up transformer cannot be used as a step-down transformer. Reason (R): A transformer works only one direction.