Welcome to the Autodesk forums.
Can you provide more details about "how" the drawing was lost?
Was it ever saved?
Do you not know where it was saved?
Can you find it, but it won't open?
Was is lost because of a crash or power outage?
You great, man: maybe this is the first ever post in the Internet history with only a title, and no text inside...
You guys aren't much help. You didn't even ask what it looks like.
O.P., what does it look like so we can help you find it. I see lots around here, but I'm not sure if any of these are yours.
Did you check the rescue shelter?
I guarentee it will be in the last place you look so I recomend looking there first.
Go to Autocad Options. on Files Tab expand the Temporary save file location
Double click and copy the text
Open My Computer and past the text in address bar.
It will open the folder for temporary or auto save files.
just sort it out by date modified or item types etc.
sure you will get a copy of your drawing there.
Thanks
Ismail