It was flown underneath the bridge and there was a fish string hanging it from below that I got it caught up in well it was dropped in water and then I let the air out completely and then put my battery back in and everything works fine for a couple of days and just till the other day it kept on losing signal now I will not pick up a signal between the controller and the drone. Can anyone give me some good information on this.

If you can I would try another controller just in case the problem is in the controller and completely unrelated to the crash but at a guess that is unlikely.
Another guess is, and I think more likely, corrosion in the drone has either damaged something or insulated something.
What sort of water, fresh or salt?
If salt I would start looking for another Mavic Mini.
If fresh you could perhaps take the drone apart and inspect it and maybe disconnect and reconnect all the wiring  and see if that does anything.
I think the actual antennae are on the landing legs but how you get to them I have not looked into.

Based on it taking a dunk in the water I'd have to bet that corrosion has already set in.  Electronics and water are never a good mixture, especially if it is salt water.  Sorry to hear about the issue.  

With a Mini 3 rumored for possible release in the April time frame you might be able to pick up a good used Mini or even a Mini 2 for a great price if you can wait a bit.

Hi, thank you for reaching out. We're sorry for the unpleasant experience. In this kind of situation, I'm afraid that you may consider sending the unit in for a proper diagnosis. You can contact our support team to start up a ticket at https://www.dji.com/support. Also, the warranty can be applied depending on the outcome of the damage assessment including the warranty period of your unit. To check the warranty period for each part, you may click this link: https://www.dji.com/service/policy. Thank you for your kind and understanding.

This is good warning for others to consider when flying under a bridge.  I was contemplating flying under a bridge a few months ago and had not thought about a fishing line might be hanging there.  Thanks for posting and sorry about your crash.  I suspect its corrosion as others have mentioned.