With your laptop's specs, it's better to just reinstall Win 7 since Win 10 is SO bloated a mere 2 core CPU with 4GBs of RAM won't cut it unless you only plan to use it for general stuff like browsing. As for formatting, you can always just pirate them or something and save yourself from all the hassle of recovery but it's up to you...
PS: To anyone who keeps suggesting SSDs and upgrades... First off, no point in paying money to update such an old model of a laptop since it's not gonna do much without first bumping up the CPU, which can't be done on a laptop, even if you have a lot of RAM or very fast HDD, it means nothing in practice since you will at most see like a 10% boost in general use if lucky. Second, hard disk speed is based on the MOTHERBOARD itself, on an old system, a Lenovo of all things (low-end motherboards so they can be cheaper), SSDs will work under-capacity, ESPECIALLY if for whatever reason it happens to have SATAII connectors and not III/6GB (even laptop SATAIII will make SSDs underperform since you will still be getting speeds equal to just over 7200RPM desktop HDDs).