How do I fix my headphone jack its not connecting headphone

@umeshraikwar you are not telling us what you have tried. I would try a forced restart first. (Make sure you have a full battery) Press and Hold down the Sleep / Power button and the Volume Down button ******at the same time for about 5 seconds. your Redmi should start to vibrate and restart. when that happens let go of the buttons. Next you want to check for any updates. Go to the settings and check for something like "Software Update" or "System Update" option. Tap on those and check for available updates.

If none of that changes anything , it is possible that the issue is your jack. There is not yet a guide for that on iFixit. You can try and work witht heis guide and get to teh jack Replacement of the motherboard of Xiaomi Redmi Note 7 Pro Motherboard Replacement

While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.