Work lost after transferring server data (help request)

[Van_Guard]

Greetings all, I want to apologise for only coming here in a time of need, but I'm most certainly desperate.

A friend and I have spent more hours than I care to admit on a private server. I recently sold the computer we were running the server on, and transferred the Tekkit Server folder to another computer. Starting up the server, (after making no changes to any properties or other files) we prepared to set off on another night of Tekkity adventures, only to find we'd spawned in without any equipment, at the original spawn point, and that all our building had vanished.

I'm hoping that some kind soul will take pity one some noobs and englighten us about how to get our hard work back, or at least put us out of our misery if we've lost something or should have copied something from AppData/Roaming?

If you're reading this and you've played a part in creating any of the Tekkit mods/ moderate the server/ support it in anyway, then on behalf of my group, YES ETERNAL LOVE FOR YOU! Thanks!