There are a couple of things here, but we can't solve your main problem - you will have to do that yourself.
But first, a couple of cahnges for you:
1) You do not need to call ToString on Text fields (or any other string datatype):
string searchtext = textBox1.Text.ToString();
When you do things like this you are just showing that you haven't thought about what you are doing. It does nothing at all, except to waste typing and processing time.
2) There are a couple of useful String class static methods which it is worth your looking at, Instead of:
if (textBox1.Text != "")
(.NET 4.0 and above only)
3) Do not concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.
When you have done this, you can look at finding the source of your problem.
Put a breakpoint on the first line of your Button Click event handler:
sql queries = new sql();
And run your program. Fill in your text box, and press the button. The debugger will stop executing when it hits the breakpoint.
Now, single step through your program and see where control goes - you can step into your
method and look at the variables as the program executes - and at each stage work out what you expect to happen before you execute the line. Does it happen the way it should? No? Then you can look at why not, and either fix the problem yourself, or you will have much better information to come back to us with.
At the moment, we have no information, and without your database (which we don't have or want) we can't check your code to get information. So try it, and let us know what you find.