mini heater ?

i bought a mini tank heater for my 2 gallon tank, it worked good for the first couple hours then the temp dropped and won’t go back up how do i fix this 

kswck22020-12-03T21:26:30Z

I don't understand why people insist on keeping fish 'tanks'  anywhere from 2 cups to 5 gallons. These are living beings for crying out loud. 
Would YOU want to spend you life in a tiny cage?  Fish need room to swim around-why? Cuz They are FISH-that is what fish Do. 
Ten gallons is a Minimum for a fish tank-20 is better. Does it take longer to clean? Yes. Is it better for fish? Yes. 
Granted, a 10 year old is not going to run a 75 gallon like I do, but Geez, give the fish some room to move around and enjoy life. 

noselessman2020-12-01T06:21:55Z

A 2 gallon tank is too small to be reliably heated and the mechanic products for them are also unreliable.  Sorry,