Thanks everybody for all the help. After about 2 hours, I think I have it fixed. I have the lighted cover but took it out just in case. I do have about 700 books on it but they were loaded over several days in batches of 100-200 with the kindle plugged into the mains overnight to allow it to index them.
I fully charged it, finally managed to check if there were any items indexing (there wasn't). I rebooted it and got the wi-fi working.
I scanned it in USB mode and did the check drive for errors thing. Then I plugged it into the computer and into Calibre and I noticed that 3 books that should have been on the Kindle were showing up as not on it. They hadn't been listed on a random search as not being indexed but I deleted them anyway.
Anyway, after this my books are back where they should be, the bookmarks are working and the Kindle is remembering my last read place again.
I'm going to put it back in the lighted cover now and hope it was those 3 books and that nothing else goes wrong! (fingers crossed!)
Thanks again for all the advice!
