QnE Optimum Database usually Located into C:\Program Files\Microsoft SQL Server\MSSQL10_50.QNEBSS\MSSQL\DATA
Anyway if you are using different instances or different SQL Server version than the folder will be in different path.
You can perform the following action to verify your data path:
1. Go to Run and type Services.msc
2. Look for the instances you are using for example: SQL SERVER (QNEBSS)
3. Right click the SQL SERVER (QNEBSS) --> Properties
4. Refer to the "Path to executable" and copy the path
5. The data folder should be located in the data folder of this path