after i changed my gamertag it contain some random number

The only way to get rid of the number would be to change your tag again and choose a tag no one else has and doesn't use special characters. You'll have to pay if you want to change it again.

Yea same thing just happened to my buddy looks like I'm making him call the support number it gave him some random gamertag after he recovered his account

You can't change the numbers at the end of your gamertag...they are simply 4 random numbers the system assigns to identify that your gamertag is different than someone with the same gamertag. ie 2 people with as their gamertag would be 4192 and 5862 (I just randomly put numbers in like the system would)

None of these has quite answered my question, I think, though I'm sure they could probably help some other people. I've played many too many matches for the player to be in the recent players list.

Second I really don't know the gamer tag (with all the crazy random numbers in some gamertags it can be quite a challenge to remember) It had some string of numbers at the end of the part I remember

I came and posted this question after searching extensively with the bit of the gamertag I thought I remembered and had no luck.

What am I looking for? All I see are folders with long filenames containing numbers and letters and a containers.index file, inside the folders are files that I need to choose an app to open, each folder contains files that also have names like the folder and one file that is called container.[random number].