"We can't open this file" Texture related

I've downloaded many aircraft over the years. I've returned to working FSX sim. I had to get a new computer running Win 10. loaded FSX onto new machine, now that I am adding add-on acft. there is a problem with texture(s) showing up. when I go into the texture files I have a white square with two blue triangle/mountains showing....when these are right clicked it reports un-able to open file. IS it a problem with win10? is there A Conversion program available to convert these to a file that is runnable in FSX