Card recovery

I have a bit of a disaster

i filmed around three hours of stuff on an sd card on Friday and cannot find the card

there are two possibilities,

i lost  the card
or
i somehow reformatted the card and recorded about an hour over the "new" card

personally I think that I have dropped the card somewhere

but I do have three possible cards that could be the same one. They are all Sandisc ones which came with an access code to a free bit of software

it is going to be bloody awkward to explain either way, and the material is irreplaceable so I really need to try to find at least part of the files

any chance? 

I have a mac mac but can access a pc