Hi, quetzalyo -
...but the last one I tried, the one that you have to send aslm, system, etc to trash to restart it the computer told me that it might not start up again....
It sounds like you may have thrown away files including Finder and System, etc., rather than the
preference files named
Finder Preferences and
System Preferences, etc. The message from the OS indicating that it would not be able to restart would tend to confirm that is what happened.
If that is what happened, and the Trash has not been emptied, you can boot the machine to a CD (or other available drive) and move those files back into the System Folder. Once that is done it should be usable again.
However, if that was what happened and the Trash was emptied, then the only solution would be to re-install the OS.
It is very important to note the exact filenames for files so that the correct ones can be addressed, rather than moving or deleting ones with similar names. Approximate is not good enough; this is one reason most of the regulars in these forums take the time to use the full, exact names for files.
Note - any time you get a message stating something to the effect that "This machine may not be able to start up again because XXXXX exists",
do not continue the restart or shutdown. The OS is not lying. Instead, cancel the restart or shutdown, and then undo the situation the OS is complaining about.