My work petition is valid for one more year.
I tried a visa extesion, as I was sent to a visit in the office back home, but my passport returned with no other visa, and my wife's L2 there were the initials CWO
How will the immigration see this when I re- enter the US?
why did they write these initials this time?
If you don't have a currently valid visa (and it seems that you do not) and you are outside the US, then it doesn't matter if the petition has not expired. You can't enter the US again without a valid visa stamp. The CWO does not sound complete, because generally I would expect it to say CWOP, which means Cancelled Without Prejudice, but I would think that CWO means exactly that - your wife's visa was cancelled (because your L-1 visa was not approved), but without prejudice to becoming eligible for a new L-2 visa sometime in the future (if and when you are approved for another L-1 visa).