All "My music" downloaded with "Available Offline" disappeared - iPhone 6S

[AfricanMartin]

Hi all, in last 6 month I have "downloaded" music in Spotify on my iPhone 6S iOS 9.3.2 - about 6 GB of music, because I am on project in West Africa, internet connection is here only as prepaid data and 6GB - just for your info - is about 30$. This week monday I run out of batery and my powerbank was also dry so tuesday when I got back home I have charged it and for some reason all my music with "Available Offline" switch on - which was really available offline till this moment was grayed our - arrow in circlu ikon was there but not green anymore. And I couldn`t listen to any music - rain season - bad or no reception due to often light outs. But in storage overwiev it looks like songs are still in phone, just the link to them got "spoiled" - at least I guess that app itself is not over 6 GB big. Do you have any idea or tip how to get it back if possible? To download it here again would be real pain, not talking about financial los... Thanks in advance