My cell phone will not show my sent messages?

OK first off i think part of the problem is that i have Virgin mobile and they do not exactly make top quality stuff but i have one of their more expensive phones x-tc and here recently it will say i have no sent messages and it has ben going kind of hay wire per say but it is seeing them and what not i don’t think i have ever gotten it wet or anything but it is a large inconvenience. i checked my settings to see if there is an auto erase and it is currently off i have even turned it on then off again to see if somehow electronically it had gotten stuck but nevertheless i have had no luck with it