i am getting this error

Question

please give me some solution for SqlConnection, SqlCommand and Clear ()

Answer 1

Don't use the connection-string property AttachDBFilename. I don't know why this option was ever invented. It's certainly nothing you would ever use in real life, that is, production.

Use the option Initial Catalog to specify the name of the database (not the path to it). It already exists in your localDB instance, doesn't it?

Answer 2

What are the fname, lname, phone, email and password? I guess that they are TextBox control?

The TextBox does not have Clear() method. Try using Text property and set string.Empty to it.

Note that mentioned above will solve only the errors you showed. There are lot of fundamental problems in use of ADO.NET. You will have to study it to obtain fundamental knowledge.

Answer 3

I would guess you have a build error. Delete the obj and bin folders. Then do a rebuild. Fix any errors.