The debug log would be helpful. You can try downloading another text editor that may be able to open larger files or compress the file and send/post it for someone to review. I just opened a 950MB text file without issue, so I wonder how large your log file has become!
#2 - verify zcashd.exe actually exists. I have had a similar problem when an antivirus software deleted the zcashd.exe file. This could be a part of Microsoft’s SmartScreen Reputation - not trusting a relatively new file on the internet.
0.9.15 was released with an updated zcashd.exe. Installing this version may restore a deleted file or work for you.
ZecWallet Lite appears to only support importing private keys for shielded addresses. I’ve generated a sample private keys for an example:
Does your public address start with zs1 or zc and does the private key look like the following:
#Private Key for Sapling Address: zs1wscnxjwfxyd9fhs0ge9evxxpz92wa2zm46f7773l65d04vy6pje7scnk3zcxtyw43vkdcwtxyuh
If you have transparent private keys, the address will start with z1 and will have private keys like below (starts with L or K).
#Private Key for Transparent Address: t1J9j1xQf4sH4rtCuRNxrVCvau4fWkJnxyf
#Private Key for Transparent Address: t1SZHo8t3ogPDqdzm1Z9ptMPdgHbS19S9Xe
If you have transparent private keys, you can sweep them into another wallet that supports transparent addresses. I personally have used Coinomi. You can find more options at https://z.cash/wallets/.