Reset 12v power supply every hour
How would i disconnect and reconnect 12vin every 2 hours to my circuit board?

Just go unplug the power every 2 hours, then re-connect it.

If you want it done automatically, the simplest is probably one of those timers you can find in home improvement stores.  They should be able to be set up to run something for 1&frac12; hours every 2 hours, for example.

If you want your own circuit to control the power, the simplest at your apparent level of electronics knowledge is to use a relay.  That's basically a electrically-controlled mechanical switch.  These things are quite forgiving, robust, and the control is isolated from the switch part.  There are lots of answers here already about how to control relays from digital signals.