Bluetooth Braille displays have disappeared

Braille on Apple Products
Good evening, Like most people I am getting to grips withhIOS7. However, I have found that my Braille displays (A focus 40 blue and Apex BrailleNote) are no longer paired to my device, which is an iPhone 4S, and when I attempt to connect them again, the phone appears not to see either of these devices. Has any one else come across this issue, and found a fix? Many thanks David