Unable to use ANYTHING in my laptop?

I’m no IT genius and I need help.
For months i have been unable to use my laptop due to something strange which has happened suddenly (without me contributing to it by pressing anything unknown). Months ago it was working normally as usual and one day when i opened my laptop i was met with a black wallpaper and all of my stuff and softwares gone. When i try to open any software which is left in the desktop, i receive an error, start menu is not even opening and right now I cannot afford sending it to a service shop. If you are familiar with what I have mentioned, please let me know what can be the solution, I’d highly appreciate it.
Unable to use ANYTHING in my laptop?
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