"...First and foremost you should not panic and seek professional help..."
In mountaineering, it often happens that due to a number of factors you get lost on your trail and thus put yourself and all those who are with you in potential danger. This situation will generally not be the first, nor the last, regardless if you are walking on a well-known path you have taken before or you are a very experienced mountaineer.
It can simply happen to everyone more than once. There are a number of factors that can lead you to this situation. Here, I would list only the most common that depend on you like not being careful enough, underestimating your capabilities and the capabilities of the group you went mountaineering with, not having appropriate equipment, not knowing the basics of orientation, experimentation in search of a shortened path and many other factors.
Also, factors due to which you would get lost, and which you can not influence are the most common: weather conditions, terrain, day and night, and more. Here you must not forget that you could still reduce the risks of these factors if you have properly considered them before you even start your journey on the mountain.
However, when you find yourself in such an unfavorable situation and your reaction to the situation depends on several measures and skills, it aids to resolve the situation more quickly and safely.
On several occasions, the instructions are that first and foremost you should not panic and seek professional help. The second important rule in dealing with the situation is not to HURRY to make decisions and deal with the whole situation, of course, if you and the group are all okay. I would add that in case of a combination of bad weather, fog, rain, snow, wind, reduced visibility, and a number of other inconveniences, the group should gather and explain the situation as much as possible and take a common position for action.
If the group is larger, individuals should be designated that will always be last, in the middle, and first in the line when moving. Then it's time to use aids like GPS, maps, apps, or anything else that might help you in this case. However, my personal advice is to always wear a compass and trust the compass, because often only that can be our way out of the situation.
In order to respond appropriately to the situation, I recommend that whenever you go hiking, whether the tour is easy or difficult, you always pay attention and observe:
Unusual things on the trail
Parts of the terrain that stand out with their unusualness and normalcy
The position of sun, moon, and stars, ie so-called orientation markers
A mental list of terrain characteristics.
This refers to things and markers that are often not marked on maps. They will serve you so that when you are in trouble you can use the memories of them in combination with the use of a compass, map, GPS, and everything else that you can use.
When it comes to moving in the snow, you can use the snow trail line in combination with a compass to determine the direction of movement. I also recommend that during the movement before you get into an awkward situation at all to use a map and identify obvious locations, such as mountain peaks, rivers, lakes, crossings through other marked paths, beginning and end of forest areas, ridges, bridges, objects, and all that is recorded on the map so that you can later use it all in navigation.
To sum up, these recommendations are just part of the solutions that were empirically the best solutions in given situations, and it does not mean that other approaches and solutions can not be used. In the end, when dealing with such situations, your character comes to the fore and you will often be remembered for how you handled the dangerous situation.