>> I think Cogwheel train to Pilatus will be closed then , so I will go to Rigi.
If you want to, you can still get to the top of Pilatus on the cableway from Kriens.
To get to Kriens, take Trolleybus #1 (direction: Obernau, Dorf) from Platform A of the bus station outside Luzern railway station. Get off at the stop called "Zentrum Pilatus".
The bus takes 11 minutes, then you cross the road and follow the well-signposted route from the bus stop to the Pilatus gondola valley station, which is about a 10-minute walk, slightly uphill.
Check the webcams for visibility before going up:
However, as you will have a Tell-Pass, and a limited time in Luzern, you might decide to go up to Pilatus or the Rigi regardless of the cloud cover, as you won't have any additional costs if you have a Tell-Pass. The trip up to the top of either Pilatus or the Rigi will still be a great experience, especially if this will be your only opportunity to experience it.
>> I wanted to see green Switzerland
In my experience, the grass at lower altitudes in winter is more of a brownish-green rather than the vibrant green of, for example, summer and early autumn. Grass at higher altitudes that is not covered with snow tends to just be brown, as the grass dies off. The deciduous trees are bare in winter, which lends the landscape a greyish look instead of the lush green you see when they are in full leaf. If there is snow cover of course, everything looks wonderful!
If you ever have a chance to come back some time between, say, July and September, you will certainly see "green" Switzerland then, at both lower and higher altitudes. Probably lower altitudes turn green before that, but I have no personal experience of spring in Switzerland.