Recovering overwritten database

I have got a file tempdb.mdf which I tried to open with notepad and I can see some of the data there,could it be that this could be the data base that Im looking for,it is about 8mb,the database that that i have which does not have any data is about 3mb.

tempdb.mdf is a system database created automatically by MSSQL to hold temporary objects. The fact that it contains some of your data is coincidental.

A couple of questions?
1. Are there actually any other *.mdf files in your SQL Data directory? 2. Do you know for a fact that your database has been overwritten?

Yes Im sure the data was overwritten coz I can ge it anywhere else,

There are other mdf

1.Master.mdf

2.Model.mdf

3.msdb.mdf

4.tempdb.mdf

5. my database.mdf

You never got back on whether Shadow Copy is enabled, because if it is you can use it to access previous versions of "my database.mdf"

Unfortunatly it was disabled,but Ihave enabled it and I Never new how it works until now, Thanks

Sorry about that defsoul, I have no more ideas apart from suggesting low-level data recovery techniques which I'm not proficient in.