Not working following server migration by host

The following information is required to get an answer:
Get this information from the PHP diagnostic (in the configuration wizard).
Gallery URL (optional but very useful): http://www.aquatic-plants.org/gallery/
Gallery version:1.4.3
Apache version: 2.2.15
PHP version (don't just say PHP 4, please):5.2.13
Graphics Toolkit:
Operating system:linux
Web browser/version (if applicable): NA

Our gallery is not functioning following a server migration by our host. It is a very old version - Gallery 1.4.3 and I just need to get it visible and functioning again. I am new to Gallery and have read through the forum and support and just don't know where to start.

A Few of the Problems:
warning and error at login - "Warning: fopen(/home/aquaticp/public_html/gallery/albums/.users/userdb.dat.lock) [function.fopen]: failed to open stream: Permission denied in /home/aquaticp/public_html/gallery/platform/fs_unix.php on line 55
Error: Could not open lock file (/home/aquaticp/public_html/gallery/albums/.users/userdb.dat.lock)!"

Album links - "Not Found
The requested URL /gallery/Drindas-125-gallon-tank was not found on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request."

We are in the process of developing a new site and eventually would like to migrate to Gallery 3 but for now I just need to get the old gallery working.

Again - I am new to Gallery and don't know where to start.

Any help would be greatly appreciated!

set to 644...not sure what they should be or that I should change them