created a sql helper class using c#
Don't use public fields. Instead, make them public properties.
Use proper naming.
What is sp? storedProcedureName will be better.
Dictionary is a collection of parameters. Therefore, use the plural name: parameters.
Using the AddWithValue method may result in poor query performance. Use the Add method with the exact SqlDbType type specified.
The ExecuteNonQuery method returns the number of rows affected. Therefore, your ExecuteResultWithParameter method should return this value.
You can get rid of the bool result variable. The failure of the method should be signaled by an exception that is re-thrown in the catch block: throw ex; (please note: the name starts with a small letter).
The ReturnResultWithParameter method has an unused sp parameter. Remove it.
You swallow exceptions with empty catch blocks. Therefore, there is no way to find out about query errors.
In all methods, you dispose of the connection and the command in the finally blocks. After that, the methods cannot be called again without re-instantiating the class.
There are extra empty lines in your code - this is also an error.
Many of the errors I described will catch Visual Studio extensions like FxCop, StyleCop, and others. They will not only find them, but also suggest ways to fix them. Start using these extensions.