I have messed the on and off times up on my thermostats I have reset the programss but I've messed it all up is there any way I can go back and wipe it all off and reset from the beginning
CM921 is a Honeywell 1 day Wireless Programmable Room Thermostat.
Use a search engine (Google for instance) and search for CM921
The first result will probably be the User Guide - a pdf document - good idea to print it off and to read through it and then have a go at programming it using the guide.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix home heating systems.