"Can I still restore the original file if I do not have timemachine?"
Sure, provided you have made a backup copy of the original file in a different location from the one which was overwritten.
If you have not made a backup copy if the file, treat this as the lesson that almost every user experiences at some time.
Things happen. Some of those things can destroy files. If the only copy is destroyed, the only way to restore that file is to recreate the file. If you've made a backup copy, you can easily restore it from that copy.
If your Mac is running a recent version of OS X or macOS, you have Timemachine—it's part of the System software. You need only set it up and provide a place for it to save backup copies of your files to start using it.
Timemachine is probably the most convenient way of creating backups—Save a document once, to give it a name and location. Time machine (If it has been turned on) will create a backup copy, then continue to save new version information as the file is edited. When the original file is damaged or destroyed, you can restore the most recently saved version o that file via Timemachine.
Regards,
Barry