[Mikez]

how can I distinguish a H from an OH group vs. H from an alkyene (there's no NMR value for it) via proton NMR only?

thank you

[stewie griffin]

The proton from OH groups is exchangeable. Take an NMR, then add a drop of D₂O to your tube and shake it up. Retake the NMR. If the H present was from an OH, the signal will be diminished or even gone. If the signal hasn't changed, then it's not from an OH.
Alkyne protons are at about 3ppm right?

[TSClimber]

D₂O is the most reliable, although if you don't have access to this often OH peaks will be broader since exchange is fast.