C:\Documents and Settings\(your user name)\Application Data\Microsoft\Internet Explorer\Quick Launch
ok here is the path where i found the orignal "show desktop" exe
iam asuming you have windows XP
ok so i guess you might have deleted the icon
you wont find it in the above folder
so here goes if you have another user account in Xp
go the same path as mentioned above but here you go to the other's
account(user name) from there you have to copy the quick launch exe
and paste it back in your respective account
hope you got it