Messed up my phone

[TheBatThatCantF]

My phone might've got messed up pretty bad so need help.
Let's start from the start--
It has been 6 months since I've been using Cyanogen Mod 12.1 and I've been quite enjoying it except the regular force stops and power downs. Now, since 2 days I can't open my phone.
Two days ago, I thought of doing a factory reset on my phone and while it was on the process, maybe the battery was low or something but it shut itself down. Now, whenever I switch on my phone it shows "To start android, enter your password". I had not given any password to it but still I entered my Google account password and it worked but it showed "Decryption failed" and then tells me to clear the data of the mobile. After that I thought thought that I will be able to clear the data from the "Recovery" menu which is the Cyanogen Default recovery but whenever I try to do it, it says
"E: failed to mount /data (invalid argument)
E: format_volume failed to mount/data, formatting instead
E: format_volume: failed to open/persist/footer
Formatting /cache...
Data Wipe Complete"
What should I do? Please help.