Any ideas why my marching bass drums lines now all sound like marching snare drums in Sibelius 5? It all worked fine for awhile and then I recently reopened a couple of files and now the bd sounds have changed.

Are you using the full version of VDL 2.5, not the VDL sounds that come with Sibelius?

Are you using the Template/Soundset?
https://www.tapspace.com/Sibelius-Virtual-Drumline-Template-525-pr-75.html

If you are using the full version of VDL, do you have an instance of Kontakt Player 2 active in your Playback Configuration (found in Play > Payback Devices)? Do you have the correct sound set selected in those instances of Kontakt Player 2.  See the Appendix of your template Readme for more information on that.

And if you answered yes to all of the above questions, are you sure that you have a BassLine instrument assigned to that staff?

I am using the full version of VDL and have the template installed.  Literally I had written everything with the correct sounds, made midi files to use etc.  Then a few weeks later reopened the file and the bass drum sounds had changed.  Everything else is still the same.  I even went into the bass line to check assignments and even though everything said bass drum when I would click on any of the sounds they sounded like a snare drum.  This seems to be occurring in all of the scores I have now.

This is running on a PC with Windows XP.

Are you sure all of your noteheads are the ones described in the template README? I would also open Kontakt Player (if you don't know what that is, click the little button that looks like a circle/starburst sort of thing in the mixer) and make sure that it has loaded all of the correct samples. In fact, I would just erase whatever it has loaded already and just load the sounds manually through the mixer. In addition to that, go to Playback Devices and make sure that for whatever reason the soundset hasn't changed. If you've done all of this and still have no success, scream ";JIM CASELLA HELP ME!"; and he'll appear and tell you how to fix your problems. ;)

Since we can't really see your system, it'd difficult to tell, exactly, what might be going on. If certain settings are changed unknowingly, it's possible that your results can become finicky. That said, here are a few details you could provide that will make a difference in gaining some sort of valid advice.

1 - You mentioned you're using Sibelius 5. Is that 5.1, 5.2, or 5.2.5?

2 - What is the exact name of the soundset you've assigned to your active Kontakt Player(s)? It's sometimes easy to confuse Sibelius's Virtual Drumline soundset with the ones that come with the Tapspace template. As Joel McAda points out above, ensuring this is assigned correctly often fixes things.

3 - What version of the template are you using? If you're not sure how to determine this, there's a [url=https://www.tapspace.com/pages.php?pageid=29]video here[/url] that explains how to check. Click on video #7.