It is not a new thing that logging into Facebook can be sometimes tough for some users, perhaps it may be that you have forgotten your password or email address and during the process of retrieving it, they are asking too much questions on security issues that is stressing you out. Here is what can be done to solve this issue;
1· First try to re-login into your Facebook account using your Facebook login details you still have in your head.
2· If the problem persists, click the link below the password box that states “Forget Password?”
3· If you can still remember the email you signed up with or your phone number connected with Facebook, then insert in into the space provided
4· A recovery link will be forwarded to your email address or to your mobile phone number depending on whichever to dropped in the box, click on the link to reset your password
5· Enter a new password twice in the spaces provided and then click reset.
6· You can now login into your Facebook account using your email address/phone number and your new password.
If the problem persist again or you didn’t receive any mail or text on your email address or phone number respectively, then it may induce that you have actually forgotten the mail address or phone number connected to Facebook.
You can then try using the Facebook login troubleshooting page or the Facebook Help Centre by following any these links; https://www.facebook.com/help/374104332645037?helpref=faq_content
From any of these pages, you can complain directly to Facebook customer service about your difficulties in logging in. I’m pretty sure they will be of help.