Originally Posted by Wikiwide

First two results in Google search:
HELP, please: N9 all messages gone. Disappeared!

Let it sit for a few minutes, like Discoveryellow suggests. Or reboot; it should solve the problem.
Look up whether you have file "/home/user/.cache/tracker/meta.db", as juiceme suggests. Unfortunately, it's not messages-DB (its location is unknown), but merely tracker-DB.
Leinad says that from his own experience... losing all messages happens so often to him on the N9 that he got used to it.

[N9] SMS and IM gone, new messages stored blank
csaavedra says that tracker-stats tell him that there are a few thousands IM and SMS messages, so they are not lost - they would just not appear in the UI..
Try query

Code:

tracker-sparql -q "select nie:plainTextContent(?d) where {?d a nmo:SMSMessage}"

Best wishes.
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