You can try the protocol explained in the kit of Promega, USA. Available online at https://www.promega.jp/-/media/files/resources/protcards/wizard-genomic-dna-purification-kit-quick-protocol.pdf. This protocol works good
The following is work even for frozen samples. I used for my work. Freeze and thaw the samples then it work fine. Read the article you get idea. Let me know if you have problems. Good Luck!!
Isolation of high-molecular-weight DNA from small samples of blood having nucleated erythrocytes, collected, transported, and stored at room temperature.(https://www.ncbi.nlm.nih.gov/pubmed/1356382)