Can't detect airport

Really thanks if anyone can solve my problem....

MB466 bought on january, running mac os 10.5.7, got a problem on LCD so i sent it to dse, where i bought it from, for repair. i have receive it today and the LCD was replaced and work perfectly.

But the problem is, i have found i cant connect to internet via wireless because the airport was set off and i cant turn it on. i have search on google for a way to do it and somebody said i just delete airport in network setting and add it again will turn it on. i tried, i delete it, and i cant add it back any more.....

i tried all the possible way except reinstall mac os and found no use because my macbook totally dont recognize the airport.

im getting really crazy on this.....Please someone help me....

I think a reinstall may be in order, but you can try running disk utility from the install disc first, repair permissions and verify the disc to see if it throws anything up. It may well be a permissions issue, but it's odd that it's happened since it's been away. I am not sure how these Macs are assembled, but maybe the repairer has dislodged the Airport card? Have you asked them about it?

i need to format whole hard disk if i want to reinstall and i need back more than 100G of data so i really dont want to do it

i tried repair permissions from dvd and it did fix many things but no use for this. probably it is hardware problem but i used apple hardware test and found everything looks alright and this confused me so i dont know it is a hardware problem of software problem

i havent ask them yet but i will do it tomorrow if i cant fix it today

You can archive and install or back up to an external HD if you have one, which would be the quickest way. Hardware test may not find a problem if the airport can't be detected anyway.
Have you looked on Apple's site to see if you can download the Airport software to replace the existing?