What kinda mags are they? Pistol, rifle, caliber, etc...
One old trick; take the ammo out, then place the mags in a WARM oven for 2 hours, then take them out and let sit for 48 hours.Lubricate with white lithium grease.
With the proper equipment, some mag springs can be changed.
But, you should never let rounds sit in a magazine for a long period of time.