math equation are displaying wingdings for symbols [SOLVED]

so I’ve been writing math equation on libreoffice to write my math lessons but at some point when I opened text document with math equations I realized this

image description

I don’t know how to fix this and I need help

edit : I use window 10 and this is a .odt

thanks in advance

Looks like missing OpenSymbol font

And to complicate matters, you don’t tell your OS nor how you saved your file (.odt or .doc(x)).

ok I’ve searched for open fonts online and found it. So I downloaded it and installed it