You have an incomplete TeX distribution, you should probably update by your package manager (miktex or tlmgr or your linux package manager, or whatever you are using)
ptmr is Times Roman (or a clone).
What is supposed to happen is that the Tex metric files are installed (I think you have that) on my system (texlive 2015) that is
$ kpsewhich ptmr8r.tfm
Then pdftex needs to know how to deal with that font, this is specified in the "map file" again on texlive that is
$ kpsewhich pdftex.map
and the relevant lines are
$ grep ptmr8r /usr/local/texlive/2015/texmf-var/fonts/map/pdftex/updmap/pdftex.map
ptmr8r NimbusRomNo9L-Regu " TeXBase1Encoding ReEncodeFont " <8r.enc <utmr8a.pfb
ptmr8rn NimbusRomNo9L-Regu " .82 ExtendFont TeXBase1Encoding ReEncodeFont " <8r.enc <utmr8a.pfb
Which tells pdftex to use the free Nimbus Roman clone of Times Roman.
I'd guess that you are missing those lines in the map file, but it's best not to edit those files directly, an update should install the right thing. (You may need to give more information about which tex distribution you have if update does not work)