If you get the following message try these steps:
"This project contained a sequence that could not be opened. No sequence preview preset file or codec could be associated with this sequence type."
Step One: Do not empty your Recycle Bin (but it might already be too late for that) hit restore on Recycle Bin.
Step Two: Make sure you have the internet. Open you Adobe Apps box, click on the Gear Wheel on the top right. Sign out then sign back in.
Step Three (if necessary) Restore your entire computer to the last updates or to the time right before the Codecs went missing,