Activate Workbook knowing only the Worksheet name

I am trying to move data from one open workbook (call it "Report") to another open workbook (call it "Data"). There are two issues; (1) the user could have many workbooks open and (2) the workbook name (Data) will always vary (users will name the "Data" file differently based on Customer name).
One thing, the workSHEET name ("Writedown") within the workbook "Data" will never change. No other files will have a tab named "Writedown". I have the code for everything but this.
For example, how do I move cell A1 on sheet1 in workbook "Report"; then find the worksheet tab/name "Writedown" among all open workbooks and copy contents to cell A1? Thank you

That worked perfectly. Sorry it took so long to say thank you, I didn't expect to get a reply at the speed of light. I spent 2 hours trying to figure it out unsuccessfully... took you less than 10 minutes to solve. Thank you very much!