Generally speaking, it is normal for a spring to lose its elasticity, which is the result of metal fatigue. If the elasticity is already very small, there is basically no possibility of recovery.

If it's not too serious, it can be like this.

If the gap between the coils of the spring that plays the role of pulling back becomes larger, the gap between the springs can be compressed bit by bit with pliers, or even "over-contracted". If the spring is under pressure, the spring becomes shorter, which can be stretched by external force and become larger between turns. This is called overcorrection, so that the elasticity will be restored and it can continue to be used normally for a long time.