I need help locating 2 Gwent cards I'm missing.

[Vurondotron]

I'm new to this website because I need serious help, I'm missing two cards and I'm having trouble looking for them. Another thing I want to ask is I don't think I played the merchant from Downwarren. Do I have to start over? Because honestly, I put so much into the game already.

1. Kayran
2. Vrihedd Cadet

If anyone can help me out I would truly appreciate it.

 

[Draconifors]

There are more merchants/innkeepers than cards you can win, so missing one merchant won't stop you from collecting all cards.

Not sure about the Vrihedd one; could be a card you need to buy, but in that case it would show under "cards missing in Velen/Novigrad/Skellige".
Kayran is definitely a card you randomly win, though.

 

[Hayashi.226]

The Vrihedd Cadet card is also a randomly-won card.
And as Muffliato said, there are more minor players (merchants, innkeeps, etc) than cards to be won from this category of players, so missing the odd player here and there isn't significant.

 

[Mr_Carbine]

You get the kayran card from Olgeird Von Everec I believe.

 

[jmcal11]

Kayran card is also random. http://gwent-cards.com/ is a good list, just keep playing merchants/innkeepers if it's not someone specific.