Plagiarism in semester exam
I think you will need to provide more information before anything else can be determined. However, a few pieces of advice can be given
First, try to read up on the plagiarism guidelines of your institution. Reach out to teachers and/or colleagues to get a better sense of how plagiarism works where you are. It is essential to familiarise yourself with the system in delicate situations like this.
Secondly, you claim that you copied and pasted a lot. You also claim that even the spelling mistakes that you made were the same as those made by others. This seems like a clear case of plagiarism, although your institution's views may differ a little. From my personal experience, even if there is an open book exam, you aren't allowed to copy-paste answers. You have to attempt the questions yourself, you can just refer to outside sources for help. Copying answers would defeat the point of a practice exam, thus presumably wouldn't be allowed. It would be advisable to admit this to your professor honestly when discussing the issue with him/her. Lying or making stories could land you into bigger trouble.
Finally, you should definitely talk to your professor, and other relevant authorities about this. Tell them the full story, apologize if you did anything wrong and then explain to them your problems with computers. If they understand your problems, you might be treated more leniently. Even if they don't treat you more leniently, it is unlikely that you will be reprimanded for trying to explain the situation.