Entire website down probably due to SQL Error or something

Hi,

Im having a problem here. My client's website http://www.ctshop.sg/ faces some SQL and scripting problem.
Im not sure how this problem initiated. All i know is that it has got something to do with SQL and the Zencart script incompatibility issue or something close to that. :censored:
The site is totalled! Cant access to admin page or anything at all!
I was told that all they wanted to do were to click on the "update zencart thingy" and then the problem arises. Will there be a possible chance to restore/recover the products and major customer's information if i reinstall the Zencart Script and use the backed up SQL restore-file (the backup file which they've done few months back)?
They've got around 1000+ products and it'll take months to re-insert the products. Please assist! this is pretty urgent as they need the websites to be up :(

"I was told that all they wanted to do were to click on the "update zencart thingy" and then the problem arises."

If the "update zencart thingy" was within their Hosting Control Panel and called Fantastico then they overwrote their previous Zen Cart installation. And if that was the case talk to their Hoster as they may have a recent backup they can install and put everything back the way it was. If not, doing a manual reinstall is the only other option.

I dont think thats gonna work. They'll only screw everything up even more. The hosting company (which my client refuses to switch to other hosting provider and i dont know why) which they farmed their web files only keep backups which only lasted for about a day or so, and it'll be updated and'll be replaced daily. Ideas off about the hosting company as i always find their services are pretty much useless.

So... I am thinking of reinstalling the Zencart Files manually and overwrite the new zencart SQL which will then be replaced with the backed up SQL files to the server (backed-up around 3 months ago). Will that work somehow? All i need is to get all the 1900+ products and the customers database back to the server....