FM2015 THAI texts only show in question marks

What did you send to the LSP? FM or MIF? If you sent MIF, open the MIF you sent them in a Unicode plain text editor (like Notepad++ or UltraEdit) and check the first line. If it's MIF 7 you're out of the Unicode world and will have to run the files through translation again with MIFs properly created from FM 2015.

If you send FM, check the files you got back from the LSP. They might have created the MIFs from the FM with an outdated "Save all files in book as MIF" plugin that still creates MIF7. This is the most common problem.

Ask the LSP to send you MIFs instead of FMs. Then check version in the MIF header. Compare it with the header of a MIF that you created from FM 2015 (via save as MIF). It's very likely that the problem came up at some point in the process when saving as MIF.

Also, open in the MIFs in a Unicode text editor (e.g. Notepad++), scroll to the end of the MIFs and check if the text is shown as Thai or as question marks. If it's question marks, you will have to restart the process with proper FM 2015 MIFs.

Also please check with your LSP which CAT tool they use (SDL Trados Studio, Across, memoQ etc.) and if the version of their CAT tool is compatible with FM 2015. All latest versions of the "big" CAT tools like SDL Trados Studio, Across, memoQ can handle FM 2015.

?Are you sure the translator used the same font as you? Because it sure sounds like they didn't & you don't have that font...