First, make sure you have a backup of the directory.
Then try this code. It assumes the first sheet of each workbook has no password to unprotect. If that is not the case, hopefully they all have the same password and the code could easily be modified to cope with that. I don't think this code will work with Excel 2007.
In the code, you would need to amend the path, the cell address you want to change and the text you want to insert in that cell.
<font face=Courier New><SPAN style="color:#00007F">Sub</SPAN> Test()<br> <SPAN style="color:#00007F">Dim</SPAN> mypath <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">String</SPAN><br> <br> Application.ScreenUpdating = <SPAN style="color:#00007F">False</SPAN><br> mypath = "C:\myExcelFiles\"<br> <SPAN style="color:#00007F">With</SPAN> Application.FileSearch<br> .NewSearch<br> .LookIn = mypath<br> .SearchSubFolders = <SPAN style="color:#00007F">False</SPAN><br> .Filename = "*.xls"<br> .MatchTextExactly = <SPAN style="color:#00007F">True</SPAN><br> .FileType = msoFileTypeAllFiles<br> <SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">With</SPAN><br> <br> <SPAN style="color:#00007F">With</SPAN> Application.FileSearch<br> <SPAN style="color:#00007F">If</SPAN> .Execute() > 0 <SPAN style="color:#00007F">Then</SPAN><br> <SPAN style="color:#00007F">For</SPAN> i = 1 <SPAN style="color:#00007F">To</SPAN> .FoundFiles.Count<br> Workbooks.Open (.FoundFiles(i))<br> <SPAN style="color:#00007F">With</SPAN> ActiveWorkbook.Sheets(1)<br> .Unprotect<br> .Range("E10").Value = "myNewText"<br> .Protect<br> .Parent.Close (True)<br> <SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">With</SPAN><br> <SPAN style="color:#00007F">Next</SPAN> i<br> <SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">If</SPAN><br> <SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">With</SPAN><br> Application.ScreenUpdating = <SPAN style="color:#00007F">True</SPAN><br> MsgBox "Process complete"<br><SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN><br></FONT>