As I mentioned, "Once you install it, open the app and it will scan your device for any text message files and load them. If it doesnt find the ones you are missing, then unfortunately they are gone."
I am afraid once they are actually deleted, they are gone. I wish there was more we could do. I pride myself on resolving all my customers issues (as my 100% positive rating will attest to) but sometimes, gone is just gone.
How hard is it to delete text messages?
Depends on the app. Some Text apps allow you to "multi-select" messages, and them delete them all in one motion, so yes, that is possible.