Well, i am only an average user with some linux experience...

There are couple of threads, where people lost their emmc through hardware fault:
http://talk.maemo.org/showthread.php...ghlight=broken
http://talk.maemo.org/showthread.php...ghlight=broken
http://talk.maemo.org/showthread.php...ghlight=broken

Even more worrisome, there are three more very recent threads with possible hardware failure.

You could try to get something from Nokia, be it a repair, another phone or money, if they are willing to .
You could try to buy a N900 at ebay or other sellers.
You could have an external microSD card to have the three partitions for Maemo like inthis threads solution http://talk.maemo.org/showthread.php...ghlight=broken .You need as large a card as you might have or get to have the space to install applications and have data on it.
The solution begins with this post to gather data from the card in use http://talk.maemo.org/showpost.php?p=944585&postcount=8 and may require some further adaptations.
You might try to get the data from the device via USB to a PC if this is still working