After the new update i have lost some of my weapons, forts, landscapes and the extra missions you have to pay for. I can't rebuy anything because i don't have enough money.

Yeah same, I purchased the bonus campaigns but after the update i had to buy them again and I don't have enough money to buy the last campaign.

I have the same problem. Lost Gravestones, Weapons, Forts, etc. I can't buy them again because I already spent all the money you get by completing the Campaign.

It happened after the new update. I hope Team17 fix it...

Don't worry, it'll be fixed in the next patch.
http://forums.steampowered.com/forums/showthread.php?t=1668338