Is there any easy way to get lost achievments back on my xbox 360 from recovering my gamertag?

i played at least 6 games offline before i decided to go back online, i had happend to go online at a friends and i had to recover my gamertag. now all those 6 games are lost and theres lke 2 game that dont even show up at all they just dissapeared. what can i do? is there anything to fix it or do i basically just have to play all the games over again.