I may have done a mistake, I was not well yesterday because of a bad news so I forgot to go extend my TR visa that expire tomorrow Sunday, and immigration is closed for the weekend, do they apply weekend grace for extensions at phuket immigration ?

I assume you mean the 60 day permit to stay (it is not a visa) you got when you entered the country is ending tomorrow. A visa cannot be extended.

If immigration is closed when your permit to stay ends you can apply for a extension on the first day they are open without being fined for a overstay. If you do not do it on that day you can be fined 500 baht for every day of overstay.

Go to immigration on Monday.  The worst you should face is a 500 baht fine for being on overstay for one day, which they may waive.  You should be able to apply for your extension after you settle the fine, if any.

I am reassured, thanks guys !