proximity sensor not working

i recently broke my iphone´s screen, i could`t use it, because every time i used it i cut myself on the shattered glass so i went to ebay and found one of the cheapest replacement screen i could find ( because i couldn´t afford having someone fixing it, or bying something of better quality). I replaced the screen, everything seemed to be going well, until i found out that the proximity sensor wasn´t working. It is really annoying when i am calling someone or answering a call, because i keep putting them on hold, deactivating the microphone or hanging up accidently. Is there any way to fix this, either actually replacing some hardware (if it doesn´t cost to much) or with a Cydia tweak.

i apologise for my any mispellings or mistakes, English is not my first language.

thanks for your help 😀