My user preferences are gone after restart I restarted my computer and it's like I have a new install.

The system tells me it can't find a telephony file and my login startup items are gone. All my Finder preferences and other settings are gone.

I am using El Capitan 10.11.6 and my home folder is on an external drive.

Has anyone ever seen this?
I believe somehow my external drive was momentarily disconnected and after I restarted it was like a brand new computer.

I restored from my last time machine backup and everything was back to normal except....my external drive was missing from the last time machine backup.

Time machine then backed up my entire external drive again.

It seems all is well now.

The moral to the story.....don't go without time machine or some other backup scheme.