I guess you would work out which model of thermostat you actually have then go searching for a manual, probably on the maker's website or with a general Google search.
Then you'd have to read the manual.
Of course, if you can't get anywhere ONCE YOU HAVE DONE THAT, you could then post a meaningful question here, probable a quesiton that includes the model of stat you have and a better idea of any symptoms you think might be cured by "resetting" it
Anon, October 2016
