older tv would like to save because i love the size the price i paid and the picture

hiiii


i have and older tv that i bought from a secondhand store it is about 52 in. it is huge and this is the problem. one day my children were in the living room watching it and they came and told me the picture went out. i came in turned it off and on unplugged it etc still no picture i just so happened to slam my hand on the tv in frustation and it came back on. every now and again the picture would go out i would hit it it would come back on. the tv was sitting on the floor the picture start to like roll down and out as people walked in the living room and if you stomped or walked to hard it would jump in and out. until one day it went off and never came back on.

my questions are

what caused this
can it be fixed
if it can be fixed is it a diy fix or professional
if professional fix is needed would it be expensive
if diy how can i fix it step by step


thanks for any help and advice given