From the druid's section on spellcasting: "You can also change your list of prepared spells when you finish a long rest. Preparing a new list of druid spells requires time spent in prayer and meditation: at least 1 minute per spell level for each spell on your list." So if the druid spell list includes Level 1 spells A-H, Level 2 spells I-O, Level 3 spells P-V, etc, then after a long rest you could go from having A-D as your level 1 spells to A,B,F, and G, or A,B, and F for your first levels and prepare I and O for your second levels. If they're on the druid class list, and you have druid spell slots of that level, they're available for you to pick from when you prepare new spells, which is usually done after completing a long rest.
When you prepare spells you are told how many spells you can memorise from all your spell levels.
There is nothing preventing you from preparing only 2nd level spells (of course, your 1st level spell slots won't be useful for casting spells in this situation).
So a druid with 3rd level druid with WIS 16 can prepare 6 spells, and all 6 of those can be 2nd level if you wanted to do it that way.
You prepare the list of druid spells that are available for you to cast, choosing from the druid spell list. When you do so, choose a number of druid spells equal to your Wisdom modifier + your druid level (minimum of one spell). The spells must be of a level for which you have spell slots.
So i had a question whether a druid can access spells from the class spell list after a long rest apart from the one already chosen and use them?
for eg: if I had 4 lvl 1 spell a,b,c,d and 1 lvl 2 spell e, after a long rest can I change the level 1 spells to a,b,f,g ?
Yes you can change your list of prepared spells when you finish a long rest for any other one available to you.
From the druid's section on spellcasting: "You can also change your list of prepared spells when you finish a long rest. Preparing a new list of druid spells requires time spent in prayer and meditation: at least 1 minute per spell level for each spell on your list." So if the druid spell list includes Level 1 spells A-H, Level 2 spells I-O, Level 3 spells P-V, etc, then after a long rest you could go from having A-D as your level 1 spells to A,B,F, and G, or A,B, and F for your first levels and prepare I and O for your second levels. If they're on the druid class list, and you have druid spell slots of that level, they're available for you to pick from when you prepare new spells, which is usually done after completing a long rest.
Birgit | Shifter | Sorcerer | Dragonlords
Shayone | Hobgoblin | Sorcerer | Netherdeep
When you prepare spells you are told how many spells you can memorise from all your spell levels.
There is nothing preventing you from preparing only 2nd level spells (of course, your 1st level spell slots won't be useful for casting spells in this situation).
So a druid with 3rd level druid with WIS 16 can prepare 6 spells, and all 6 of those can be 2nd level if you wanted to do it that way.