in my pattern it says leave remaining stitches on a thread can you please tell me what exactly am I supposed to do is the thread detached or still attached thanks for your replies
What are you making? There are thousands of patterns so if you have a pattern name and link it would help us answer you when you ask questions. 
Usually when a pattern says that they want you to take another long piece of yarn and thread it through some stitches that you will work later. Whether you leave the working yarn attached depends on the pattern. For some patterns you leave it attached and use a new skein, with some you cut it.