If i lose mass effect 2 do i have to start over?

In mass effect 2 when i lose the ending do i have to start all over.Because when i did the ending everybody died.If i lose mass effect 2 do i have to start over?
Yes unless you have multiple save files which you can go back to. You should have upgraded your ship and been a better commander.If i lose mass effect 2 do i have to start over?
If u died at the end of part 2, apperently in part 3 u play as some other character and not sheperd.If i lose mass effect 2 do i have to start over?
Yes.

xbox 360