Hello Jas,
First thing that you want to try before assuming it's a hardware problem is to hard reset your phone. You can do this by holding the Power and Home button for 10-15 seconds, or until the screen goes black and the Apple logo shows up again.
Second, try to plug in a pair of headphones into the headphone jack and remove it after. Sometimes, the headphone jack may appear to be "stuck" because it still thinks there are headphones in the phone.
If these troubleshooting tips did not work, then I am afraid it may be a broken headphone jack. Unfortunately, since the headphone jack is tied to the lightning cable flex cable, you have to replace the whole flex cable. iFixit has the part available on their website if you look up the product code IF124-010-1 in the search bar, but I recommend eBay/Amazon because it is significantly less expensive.