So I bought the land from the jarl of falkreath and I'm a Thane. When I finished talking with the jarl I saw Rayya but didn't speak with her.. So I went to the land and just improved the small house.. But where's Rayya? It's been like a week of game hours and she still isn't in the house.

Note: I only build the wall, door, roof and such. Didn't bought any furnishure!

Can't anyone help me? Thanks!

she might have died. there are random dragon and vampire attacks. many NPCs can die by random attacks.

Most Hearthfire housecarls tend to explore around.

M'aiq's second favorite follower, Valdimar (a Hearthfire housecarl), was exploring Ustengrav before. M'aiq told him to follow him and dismissed Valdimar. He returned back to Windstad Manor.

I'm not completely sure on this, but you may need to build more on the house before she will move in. I think there may need to be at least one bed in the house first; you possibly may need to furnish upstairs area in the main hall too.

You don't need to. M'aiq did a test.

He made Rayya follow him, built the small house, and dismissed her. Rayya just patrolled the area and guarded the small house. She could sometimes be found inside the house, with or without furnishings, it does not matter.

That's good that M'aiq tested it.

The Hearthfire DLC Houses automatically have Housecarls? I've built Lakeview countless times, never once has there been anybody there that I haven't appointed.

The More You Know.

You have to become Thane in the hold prior to getting a housecarl. If you are already Thane, then something else is wrong, probably a bug.

You have to speak with her first.

If you didn't, she will still be waiting in jarl longhouse.