zikr = "" & TextBox1.Text & ""
Workbooks(zikr).Worksheets(zikr).Range("A1:Z600"). Select
Selection.Copy
Workbooks("Trend (read only)").Worksheets("Data").Range("A1:Z600").Paste

or

Workbooks(textbox1.text).Worksheets(textbox1.text) .Range("A1:Z600").Select

its coming up with an error, the value of textbox1 is the name of the
worksheet, and i have tried both with and without the quotations..