Blinking Blue Light (big one), Drive Invisible on network

Hello all...
I have had my 5Big Network (10TB) for 3 years now (set up in my home). I am not very computer savvy but do try to fix issues if I am comfortable (& have proper guidance)...The unit has worked fine (my wife archives all our videos & photos) until now. I tried to access it recently & without warning, it has vanished from the network! It has just a flashing blue LED (large one in front of unit). After I tried turning it off & then back on, it seems to power up just fine, the 5 separate LEDs (one for each drive) first flash red/blue & then one by one flash blue & after about 5 minutes or less, they remain steady blue. The large LED in front flashes blue every 0.5 seconds (for days). I tried rebooting the 5big unit several times, I rebooted router, I connecting the 5Big directly to another PC via ethernet cable. Nothing....I cant locate it, it's invisible. Just the 5 steady blue LEDs in back & large blinking blue LED in front. I do not want to do anything further for fear of doing something wrong. Please can someone help, I do not want to lose any data either! (happy wife, happy life) :please
I have had my 5Big Network (10TB) for 3 years now (set up in my home). I am not very computer savvy but do try to fix issues if I am comfortable (& have proper guidance)...The unit has worked fine (my wife archives all our videos & photos) until now. I tried to access it recently & without warning, it has vanished from the network! It has just a flashing blue LED (large one in front of unit). After I tried turning it off & then back on, it seems to power up just fine, the 5 separate LEDs (one for each drive) first flash red/blue & then one by one flash blue & after about 5 minutes or less, they remain steady blue. The large LED in front flashes blue every 0.5 seconds (for days). I tried rebooting the 5big unit several times, I rebooted router, I connecting the 5Big directly to another PC via ethernet cable. Nothing....I cant locate it, it's invisible. Just the 5 steady blue LEDs in back & large blinking blue LED in front. I do not want to do anything further for fear of doing something wrong. Please can someone help, I do not want to lose any data either! (happy wife, happy life) :please