Latitude E7440 not charging

Hi everyone!

Ive been having issues with my laptop recently

I've tried charging it but it doesn't seem to charge. It is on 3% so I can't do much with it. The laptop comes on but it obviously needs charge however when I put the cable in, it isn't detecting anything. No charge indicator or anything comes on whatsoever. I think the charger is fine because the yellow light comes on when I switch it on and nothing seems to be wrong with the power bank or cable. 

I've tried the following:

-I've switched it off, removed the battery, pressed power off for 20 seconds and that method didn't work.

 -I've bought a new charger and that didn't work either. 

-I've tried removing the battery to see if it would charge the computer/keep it on with the charger but nothing happens it is unable to do that it just stays off.

-I've bought a replacement battery and it works but the laptop is still unable to charge with either charger. 

Does anyone know what the problem can be???

I've read that the issue could be with the charge port and it may need replacing. I've looked inside and nothing seems too strange, I've noticed the golden prongs (4 of them) inside are flat and some people say they can get squished inside so you can pull it out so it allows for a proper connection but idk if I should do that. I can't find a proper diagram online to tell if the prongs should look like how mine are looking so I don't want to risk it. 

Any recommendations on what to do next?

I've got loads of data on here and I need it for school so i don't want to lose it! 

Thanks in advance!