Mountain peaks are exposed to high winds and often covered in snow. They provide neither food nor shelter. Climbing rock and negotiating ice and snowfields calls for special skills, which are best learned first-hand in mountaineering schools and practiced under supervision. No inexperienced person should think of trying to tackle real mountaineering territory, except as a learner with a properly organized party. But disaster may leave you on a mountainside or force you to cross a mountain range to get to safety.
If no rescue is likely, the first aim in daylight should be to get down into the valleys where food and shelter are available. At night and in bad visibility this is too dangerous. Some kind of shelter must be found until visibility improves.
Dig into the snow if there is no shelter among rocks and no wreckage to provide cover. If below the snow line you must cover yourself to prevent exposure. A plastic bag will make an improvised sleeping bag, if you have no survival kit. Salvage blankets or covering from a crashed plane or use any clothing to cover yourself as much as possible, but do not pull clothes too tightly round you; air within the clothes will provide insulation.
On a slope, sleep with your head uphill; on rough and stony ground sleep on your stomach for greater comfort.