SQL Database File Not Created and Not Opened

I think you need to add database name in your connection string(check credential also). Secondl make sure that *.mdf and *.ldf is present in correct directory. Follow below links that may help you to resolve:

 

http://stackoverflow.com/questions/9509441/an-attempt-to-attach-an-auto-named-database-error

 

https://forums.asp.net/t/879454.aspx?An+attempt+to+attach+an+auto+named+database+for+file+failed