Countdown timer

I am new and don't know whare to begin I have looked all over the Internet and am coming up short I need to build a count down timer that displays weeks hour min and sec with a max of 4 weeks that can not be stoped once started on a 16x2 lcd I had planned on using 5 button 1 for weeks the second for hours and so on and the 5th to start it and when it is over it turns a servo. So once you hit the start the servo turns to the left and stays their till the time is up then turns back .

Can anyone help me?

Weeks, hours, minutes, and seconds?

Not weeks, days, hours, minutes, and seconds?

I guess it would be better if in stead of weeks ot make it days if it is possible for example the display would look like this as it is counting down until it reaches all 0s the would turn the motor and be ready to enter a new time up to 1 month max is it even possible?

Day. Hour. Min. Sec.
3. 20. 30. 05

This project was done in a thread a few months ago. A variation happens like clockwork.
You might be able to find any of them with a search. Be prepared to get an RTC module or shield.

Ok so I got a ds3231 rtc and a new 2x16 lcd with l2c interface module now I have been playing with some code but no luck I think I am starting in the wrong place can you tell me where to startOk so I got a ds3231 rtc and a new 2x16 lcd with

Start by going to the search bar at the top of this page and enter Countdown Timer, somewhere in the the "about 953 results" will be some good starting points.

Personally I would probably start by using the programmable square wave generator set to pulse once per second (or at what ever fixed rate I can get) and then decrement a cascade of variables, count down from 59 seconds to zero, when "seconds" = 0 Decrement minutes and reset seconds to zero, when "minutes" = 0, decrement hours by 1 etc.

But I haven't read all the posts regarding countdown timers so there are probably easier ways.

A quick search also found this, maybe worth a look.
edit added hyperlink: