Database not found

Question

Please i am opening program but the database can't open this is error that i a get fro sql express

 

"The header for file 'C:\Users\ELITEBOOK\Google Drive\Code-MailClient\App_Data\MailClient.mdf' is not a valid database file header. The PageAudit property is incorrect.
An attempt to attach an auto-named database for file C:\Users\ELITEBOOK\Google Drive\Code-MailClient\App_Data\MailClient.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share."

 

please help will be greatly welcome.