I copied photos on another external hard drive but they have been coped as ending with .icloud.. Now i can not open tham. Never used icloud for this process although I have an icloud account

If you select the file, then tap the return key, then edit the file name to remove the .icloud, and then tap return again, will they open? Or replace the icloud with jpg or the appropriate extension?

You are welcome. If you still have the original photos, try making a copy of the original, put the copy in a folder, and copy the folder to the external drive. Does that work?