Proto-Indo-European *dn̥ǵʰuh₂- "tongue" became Proto-Germanic *tuŋǥon, Old English tunge, and then tongue. The substitution of o for u before the n was a medieval scribal habit to avoid too many vertical strokes in a row.
In Latin, the root became lingua "tongue, speech, language". The change from /d/ to /l/ also happened with PIE *daḱru- "tear" becoming Latin lacrima. lingua became Old French langue, then langage, borrowed into English as language. The -age suffix is also found in baggage, carriage, damage, etc.
Dńghū is a group interested in bringing a "reconstructed Proto-Indo-European language to its full potential, and teaching it as a second language for all European Union citizens." They call this language Modern-Indo-European. I wonder what the Basques, Finns, Hungarians, Estonians, Maltese and Turks think of this.