Guild Wars 2

I have level 19 ele for fractcals. When i hit level 20 will be able to do daily reward at 10 then again at 20? If this is true can i switch toons and get daily rewards on that toon?

Yes to your first question. There are multiple dailies, one for every 10 level. So you can do the same day the daily for 1-9, for 10-19, 20-29, 30-39, 40-49.

However, concerning multiple characters, you only get access to the daily that character has access to. So let’s say you have a character who has access to level 20, and an alt who has access to level 1 only. You can do 3 dailies with your main (1-9, 10-19, 20), and only one on your alt. Even if you do a level 20 on that alt, you’ll get the reward for a level 2 daily, as he only has access to that range of daily.