imac does not start after I deleted login plist

Removing either the loginwindow.plist (or the loginitems.plist) in the User or HD Libraries shouldn't prevent booting. Can you confirm exactly which item you trashed? Maybe find that thread where you saw this suggested? Was it one of these?

/Users/yourusername/Library/Preferences/loginwindow.plist

/Library/Preferences/com.apple.loginwindow.plist

Are you saying it won't boot into 'safe boot' holding down the shift key? It should still do that, even with a Bluetooth keyboard.

Failing that, and if you haven't got one, can you borrow any usb wired keyboard just while you troubleshoot the problem?

Not optimistic, but you could try a PRAM reset: https://discussions.apple.com/docs/DOC-3603

I don't suppose the wireless keyboard has turned itself off - it should work.

I still don't understand why it won't boot, but if it's still in the Trash, as you say, you might try the following.

The following applies only if the loginwindow.plist you trashed was found in the HD Library, not your User LIbrary.,

Boot into single user mode. Hold down Cmd-s at the startup chime. You will get a screen with text only.

At the prompt, which will end in root# enter the following. (For this, the fsck -y ,keep entering that and hitting return until you get a message "The volume***** appears to be OK" )

NOTE:If you get

fsck_hfs: Volume is journaled. No checking performed.

fsck_hfs: Use the -f option to force checking.

Then just go ahead and enter the next command. Don't wait until you get "The volume*******appears to be OK."

fsck -y

next enter and hit return

mount -uw /

Then, finally, enter

mv /Users/"yourusername"/.Trash/Library/Preferences/com.apple.loginwindow.plist /Library/Preferences/

(IMPORTANT: In the above command, there is a space after /com.apple.loginwindow.plist and before /Library/Preferences/)

Only put yourusername in quotes if it has spaces, otherwise the quotes are not needed.

When the root# prompt returns, enter reboot and hit return. (And pray)

Note: all of this, except for your user name, which will depend on what that is, must be entered precisely as given, noting case and all spaces or lack of. After hitting return for each of the given command wait until you get a new prompt.

Message was edited by: WZZZ

If that's the case, it has to be some other problem. In Mountain Lion, 10.8, the User Library is hidden by default. Did you have to do something to get to it? If you didn't, then it was most likely in the HD Library, which is not hidden.

Even if it was from the User Library, I would still boot into single user mode and run the fsck -y until it comes back clear. Then reboot. That might be enough to fix it.

I still have very strong doubts that trashing that file from either Library is the cause of your problem. Why don't you provide a link to the thread where you found that suggestion?

Message was edited by: WZZZ

I don't understand what you mean. Are you in single user? Try just entering it like that, even if it goes to the next line.

OK, those were in the home folder library. The instructions I gave you won't work. Besides, it is virtually iimpossible that trashing those two files would prevent booting. You must have done something else, or by coincidence some other problem appeared just at this moment.

Just try running the fsck -y, then reboot.

No skype here.

Maybe I'm not understanding something about this--I only looked through the thread very briefly--but I don't see how this thread you linked is even remotely related to the problem of connecting to your wife's computer. And I'm not ready right now to start in with that one.