Lost my tech points...now how to get them back?

In response to your question, sometimes the game gives you "island events" that can take away all your hard-earned tech points.

There is only one wasy to earn tech points, and that is to place villagers at the research table to research. You can set their preference as a scientist on the "Detail" screen, that way they gain experience as they work.
Usualy they won't stick with the work at first, but keep dragging them to the table until they catch on. Then to make sure that they will continue to research after you log off, click on them and watch the "action" screen. After the "this villager has gained experience" action shows up, it will usualy way they are doing nothing. Wait, then if they choose to research they understand and will keep doing it on their own.
Another way is to wait until their skill is shown as "trainee scientist", (their preference has to be set as scientist first.)

And then it's just a matter of time until they begin earning tech points by researching.

Hint: You can change the speed of the game in the options menu on the main page/entrance page of the game to "fast", if you will be checking in soon, otherwise they might die of sickness or starvation.

Hope that helps.

You can also gain tech points by island events.