20 yr old specialized rockhopper needs new crank gears
The "front pedal crank gears" are called chainrings. Just searching for the word should find several options.

There are several different bolt circle diameters for 5-bolt mountain bike chainrings. It's best to measure. Aftermarket parts from brands other than Shimano are fine, look for chainrings designed for 8 speeds or less and correct bolt circle diameter (BCD).

For changing the chainring, you need a chainring bolt tool to keep the other side of bolt from spinning.