|Use 'Total Commander' or filemonkey or any file management application which provides 'Search & Replace' feature.|
You will have to do it in two passes.
Here are the steps for the first pass:
1 Select the directory
2 With right click of mouse select just the files Track01 thru Track09
3 From Menu on top select Files->Multi-Renaming Tool...
4 All your selected files should be there under columns 'old names' and 'new names'
5 On the top menu in the box 'Search & Replace', in the 'Search' enter "Track0" (without quotes)
6 In the 'Replace' box enter "812508013181_" (without qoutes)
7 Confirm in the column 'new name' the filenames are changed to your desire
8 Press 'Start' and the files will be renamed, press 'close' to go back to the directory,
Pass 2, with the right mouse click pressed select the files Track11 thru Track 21
repeat steps 3 and 4
5 in 'Search' box enter "Track"
6 in the 'Replace' box enter "812508013181_"
do steps 7 and 8.
Hope it resolves ur issue