Get a thermometer to measure the temperature - I recommend a digital kind with a probe. Get a hygrometer to measure the humidity. There are also cheap stick on kinds you can buy but I've heard many advise against them. You can get combo thermometer/hygrometer set ups. Your petstore should be able to help you. You want to measure the temp on top of the substrate above the UTH to see what the temp would be if your bp were lying on it. You want it to be 90 degrees on the warm side. Also measure the tempo on the cool side.
I don't mean to harp, but it is possible that the environment is a contributing factor to your bp not eating. I'd say make sure you have all of it straight, make sure there are at least 2 hides (one on each side), make sure your cage is not in a high traffic area, leave your bp alone for awhile, make sure it's not in shed, etc. If you're still having problems, maybe its just going off feed like many do this time of year. Again, see if it will eat at the petstore. As a previous poster asked, how and when are you feeding it? There are many methods to enticing a BP to eat (cover tank, feed at night, feed in bag, etc) that are available on many care sheets.
Good luck!
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0.0.1 Ball Python
1.0.0 Kenyan Sand Boa "Gimli"