Troubles modifying my assembly

[Anonymous]

Hello everybody,

I'm working on an assembly of cameras and some tooling, I've created almost all the parts of the assembly but I stopped for a while, meybe an hour; now I'm not able to modify anything, mi screen displays this message: "Cannot modify the library file C:\users\frank...(etc)... Component is not checked out to you. Edits are not allowed on this file"

I'm really confused, I tried to place a component that is in .DWG format, it request to write a path for the file, after this I can't do any modification.

Please if somebody knows why this is happening or how to solve it I'll appreciate all comments as son as possible.