Westron (Sōval Phɑ̄re) and Adûnaic are both moderately developed, though very little appeared in The Lord of the Rings itself, and a good deal of the material still isn't available now.
Adûnaic
Adûnaic is probably the most attested non-Elvish language of Tolkien's. Most of what has been published for this language can be found in the posthumous volume Sauron Defeated (The History of Middle-earth vol. 9). There you'll find a few short translated texts, several writings that feature a high number of Adûnaic names, the first 17 pages of an unfinished Adûnaic grammar (which breaks off mid-way through the declension of nouns), and Christopher Tolkien's notes summarizing everything else he can find about the language.
I'd point to Eldamo's page on Adûnaic for more info.
Sōval Phɑ̄re
For Sōval Phɑ̄re, or Westron, even less is available, and nearly all of it unpublished. Tolkien developed this language a bit while working on Appendix F of The Lord of the Rings, which was originally meant to go a lot more in depth on this language, more than just the handful of words given in the published book. Some of Tolkien's drafts for Appendix F are included in The Peoples of Middle-earth (The History of Middle-earth vol. 12), though Christopher Tolkien was pressed for space in that book and left out the bulk of it. There's a few dozen pages available in the Tolkien archives at Marquette University (Mss-4/2/15), and based on that there was an unofficial analysis of its grammar (also mostly focussed on nouns) and vocabulary published in 2001 in the fanzine Tyalie Tyelellieva (no.17), but the material still remains unpublished beyond that.
I'd point to Eldamo here too, but Eldamo only considers officially published material, and so only represents a sample of Tolkien's work on the language.
For both languages though, there's enough to get a feel for the style of what Tolkien saw the language looking like, but not enough to translate arbitrary sentences into.