can anyone tell me please that if i update my krita to new version will i be able to use the files from the previous version?
Well, it depends on what version you currently have. But I just opened a kra file from 2013 with the newest version of Krita without issues. As far as I know Krita has always been backwards compatible. Opening newer files with an older version of krita can be a problem though, when the file contains data for features that didn’t exist at the time.