corupt save

[galaxikiller]

i played this game a verry long time ago and left it unfinisched now i picked it up again but somewhere in de middel of the story line i come against some trobbles like picking up c4 but can not select it again in the inventory and after quiting the game and restarting it it says that the save is corupt my 3 questions are;
1. are there ohter people whit this problem and how to fix it?
2.if i start a new game will it keep my online progress or not?
3.must i delete all save and game data from my system and start again but than i think i lost all my online progres to is it not.

thank u in advance