If any extra wiring or additions to the house were done are you sure you don't have a small Fuse box or extra Breaker Panel in another part of the house or basement? The only other thing I can think of is the breaker didnt trip and the wire connected to the back of the plug socket that the CHE was plugged into fouled that socket.. If the electricity cant make a complete circuit then those rooms on that run wont work. Turn off the main breaker (to the whole house) and pull that plug out of the wall and see if its burnt. If it is they are $2 at Lowes ect... 5 min job. Look up changing a Plug Socket on youtube....