Remove stem and crown from swiss legend Neptune

Why not to go to repair shop and pay them a couple of bucks? For these they'll clean it with high pressure air in addition :-)

Probably 395 or 371

Send it back... It shouldn't do that, it has a broken setting lever.

If the day will not change when you pull the crown out to the first position (try both directions) then pull the crown out to the second position. Advance the hands until yesterday shows in the day window. Now set the date by putting the crown in the first position and set it to yesterdays date. Now advance the hands (position 2 until the date and day change and then set the time. Done

In order to replace the crystal on your watch you are going to have to remove the entire movement and use a watch press to remove the crystal.
this is not an easy job and should be done by a professional
First you will need to get a watch back opener to unscrew the back of your Tag. The three slots should fit into the back of the watch. tighten the opener until it is firmly on. then turn counter close wise until back of case comes off.
Next you will need to remove the watch hand and crown. Becareful doing this for pressing to hard will break your set leveler. You will need a thin pin pusher and look on the back of the movement for an arrow pointing toward a hole in the movement. Push down and at the same time pull the stem and crown out of movement. turn the watch right side up and the watch movement should fall out. Place movement on a very safe spot so not to damage movement or dial
now you will you be ready to remove crystal Since it is a friction crystal you will need to do use a watch case press . find two die that fit exactly the watch and crystal use a scooped side and place it on the bottom side of the watch press. Next use a flat die to place on top of the case press. place the watch face down. you will be pushing the watch crystal out from the top. Press down on the level and check to see if the crystal came loose, keep doing so till the crystal comes out.
finally you will need to measure the thickness and diameter of the crystal and find the exact size. I believe this watch has a sapphire crystal so you will need a sapphire crystal too.
Once you buy the proper crystal it is time to put the it in the watch. Place the watch face up in your watch press. and slip the crystal in through the top making sure its perfectly even all around. Slowly push down on the leveler until proper pressure is applied and the crystal snaps in.
Now you have new crystal . Clean crystal thoroughly and the inside of the case. Place watch upside down carefully place movement back in. slide spacer in . Now slide watch stem and crown back in push down again on the set leveler with pin pusher.
Place case cover on back and tighten properly to prevent water or moisture from entering and you are done.
This repair should be done by a professional especially on such a nice watch. Any watchmaker can do this job and will have the tools to do it properly

while the crown is in normal position turn the crown clock wise

That small gizmo is called CROWN or WINDING CROWN. It is not possible to obtain it online, so, you have to shop around for it. Find your nearest watchmakers shop and ask for replacement. You may need stem as well.
Rate, please.

I contacted the manufacturer. You remove the crown, then use tiny attachment to a bike pump to push air into the interior of the watch. This will cause the crystal and dial to come apart. Viola!