What kind of antenna?

An old 27/40/75MHz receiver has a simple wire, you can solder the pieces together again but it is better to replace the whole antenna for a fresh wire.

The same counts vor a 2.4GHz antana made of a simple wire.

2.4GHz antenna's based on a coaxial cable just need a 3cm (from the shielding) stripped end piece. to be a new antenna again. If it is plugged to the receiver board you can find new antenna's from many brands.