Can't see my match history?

I've had a similar issue before. I would recommend trying to look at your match history in a different browser.

If that works, go back to your original browser and remove na.leagueoflegends.com from your browser history/cache/cookies. If you happen to use Firefox, this is as simple as Ctrl+H, right-click and na.leagueoflegends.com page and select "Forget this page".

Same here, and I can't access the champion store either, meaning I can not buy ward skins or champions in general.

Is this the same for you as well?