Equivalent of JavaScript GetElementByID in C sharp

Question

Hi,
I currently have a form page containing dynamic controls. The form consists of both Dropdownlists as well as textboxes. When creating the form dynamically the IDs that I have assigned to each of the controls is A1, A2...
I need to retrieve the selectedvalue of the dropdown list and the text in text textboxes to save the data off to the database.
I am unable to access the control in my code behind page.
Could someone please tell me if we have something equivalent to the javascript getElementByID in C sharp?
Thanks
Aditi