All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
We have already issued Fatwa 82812 clarifying copyrights, so please refer to it.
However, we do not object to the student copying the whole book or part of it for study and for benefitting from it, especially if he needs it but he can not afford to buy it.
This is so because the authors and publishing houses usually reserve the copyrights for commercial printing or copying.
If a student photocopies the book or part of it for private use and not for commercial use, then we do not think that such is what the authors or publishing houses reserve for themselves as copyrights.
Indeed, some scholars are of the opinion that it is lawful to copy of a book if the purpose is for private use, especially for the students who seek Islamic knowledge.
Having said that, we think that it is lawful for you to allow the students to make copies of your books for the purpose of studying.
As for the copies you yourself made before knowing the ruling concerning the copyright, then there is no sin on you because of your unawareness of the ruling of prohibition in general.
Nonetheless, you should not throw away what you have already photocopied as this is spoiling money without right.
Allaah Knows best.