online problem !! please help :(

I have problem with Forza Horizon 2, I can’t go online and everytime I try to download a car from the marketplace it shows an error ?? could someone help please ?? Am I banned or what ? is the server down ?? please help me

Sounds like maybe you’re not quite synced up or something since you’re on Xbox One. Try these steps:

1 - in the Dashboard and out of all activities, push the Big X button on the console itself and hold until the unit shuts down.
2 - disconnected the external power pack from either the wall or the wall-side connector so there is no power to the pack itself. You can tell when that has drained because even the dim orange light will be out.
3 - wait about 90 seconds, then reconnect the power pack to the electrical connection and wait for it to power up at least to the orange glow again.
4 - now start your console as you normally do. This will force a full system check, and may result in time to redownload or update components. DO NOT do anything until the system settles back to the Dashboard and suggests you can logon.

IF there is any update or syncing of the game, DO NOT PLAY until that is completed. That can take anywhere from a few seconds to a few hours, depending on how much needs to be synced. DO NOT interrupt the process, and DO NOT QUIT out of the process before it is completed. In some cases, this has taken people up to six hours or so.

If that doesn’t solve the solution, since you haven’t mentioned if other games are playable or not, nor anything regarding your Internet access, router/modem/gateway, and whether you’re wired or wireless to your networking device, try this information: Xbox Support

There is also a link within the networking support from Xbox to drill down to your make/model and brand of the networking hardware.