When you save a project, that .pds file is a roadmap that tells the computer 3 things...
1) Where to find the files used in the project.
2) Where to place the files in the timeline.
3) Titles, menus, whatever "native" PD fx used.

If you move your files, PD can't find them, and replaces them with a black box.
You are really screwed, unless you can remember each clip and browse to it.

In the future, resist moving files around.
Also, if you must abandon a project for a while and must move files to other places, look into the Pack Project Materials function.
PPM will take your entire timeline and place copies of all your files that are currently in that timeline, into a home folder, all self-contained. If there are other files not yet used for that project, but related to that project, and you wish to keep them all together, you must copy those to the PPM folder for future use. After that, and being sure all materials are present in the PPM folder, you can delete the originals, if you desire. This is the definitive PPM post. HP Envy Phoenix/4thGen i7-4770(4@3.4GHz~turbo>3.9)
Nvidia GTX 960(4GB)/16GB DDR3/
Canon Vixia HV30/HF-M40/HF-M41/HF-G20/Olympus E-PL5.
Tape capture using 6 VCR, TBC-1000, Elite BVP4+, Sony D8 camcorder with TBC.
https://www.facebook.com/BarryAFTT

Hi Barry thanks for the reply. I have one drive for current unfinished movie files and another for burnt and finished movies I sometimes want to re-edit a finished movie using the original timeline files which i have saved in the second drive.
Can you tell me where i can find and how to use the Pack Project Materials function'
It looks like if i can't use this feature i will have to store all current and completed & burnt movies in the same drive?
Thanks..........Tom

With your project sitting in the timeline, click on file (top menu) then select export and select Pack Project Materials. Then you will be asked to select a folder to save to, pick a folder or create new one. Done! HP Envy 17
Win10 Pro (64-bit) Intel i7 Core - 4510U @ 2.00GHz 2.60GHz
16GB ram
PowerDirector 11 Ultra 64-bit ver. 11.0.0.3625
Cyberlink Power2Go Deluxe 7.0.0.1827
PowerShot SX40HS
Canon Vixia

Using the top-left menu choices...
File>Export>Pack Project Materials.
The program will then commence making copies of the files in the timeline, to a folder of your choice. I always name the folder with a "ppm" ending. Inside that folder now will also be a newly created PDS, so at that point, after creation, you can move that folder anywhere you want, it will open the project from that location. Don't forget unused (but related) files. HP Envy Phoenix/4thGen i7-4770(4@3.4GHz~turbo>3.9)
Nvidia GTX 960(4GB)/16GB DDR3/
Canon Vixia HV30/HF-M40/HF-M41/HF-G20/Olympus E-PL5.
Tape capture using 6 VCR, TBC-1000, Elite BVP4+, Sony D8 camcorder with TBC.
https://www.facebook.com/BarryAFTT

Thank you. This will be a big help....tom